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Diagnostic Aids

Perform this test only when instructed by QUICK TEST or directed by other test procedures. VCRM is located in left front of vehicle behind front grille. This test is only intended to diagnose following.

Refer to illustration for VCRM connector terminal identification. See Fig 1. For VCRM terminals and wiring identification, see WIRING DIAGRAMS. To prevent replacing good components, be aware that the following unrelated components or systems may be at fault.

Fig 1: VCRM Connector Terminal ID (XB1)
G93A28886

1) Check Battery Supply Power  With Key On Engine Off (KOEO), set DVOM on 20-volt scale. Measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.

2) PCM Ground Fault Isolation  Ensure ignition is off. Install breakout box, and connect PCM. Set DVOM on 20-volt scale. Measure voltage between positive battery terminal and SIG RTN terminal (Gray/Red wire) at Data Link Connector (DLC). If voltage is less than 10.5 volts, go to next step. If voltage is 10.5 volts or more, go to step 10).

3) Check Continuity Of SIG RTN Circuit  Turn ignition off. With break-out box installed, disconnect PCM. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal (Gray/Red wire) at DLC. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

4) Check PCM Ground Circuit  Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between negative battery terminal and test pins No. 40 and 60 at breakout box. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ground circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

5) Check Internal PCM Ground Circuits  Turn ignition off. With breakout box installed, reconnect PCM connector. Measure resistance between test pins No. 46 and 40 and between test pins No. 46 and 60 at breakout box. If resistance is less than 5 ohms, system tests okay. Remove breakout box. Reconnect PCM, and repeat QUICK TEST. If resistance is 5 ohms or more, replace PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

10) Check Continuity Of VPWR Circuit  Turn ignition off. With breakout box installed, disconnect PCM connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 7 (Red wire) at VCRM connector and test pins No. 37 and 57 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit between PCM and VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

11) Check For B (+) & IGN START/RUN Power To VCRM  Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure voltage between terminal No. 6 (Yellow wire) at VCRM connector and negative battery terminal. Record voltage reading. Turn ignition on. Measure voltage between terminal No. 17 (Red/Light Green wire) at VCRM connector and negative battery terminal. If both readings are 10.5 volts or more, go to next step. If any reading is less than 10.5 volts, turn ignition off. Repair open in B (+) or IGN START/RUN circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

12) Check VCRM Ground (Terminal No. 16)  Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure resistance between terminal No. 16 (Black wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open ground circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.

15) Continuous Memory Code 584  Continuous Memory Code 584 indicates VCRM PWR GND circuit is open. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

Clear continuous memory. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 584 is present (hard code), go to next step. If Code 584 is not present (intermittent), go to step 18).

16) Check Continuity Of VCRM PWR GND Circuit  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 1 (Black wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open in ground circuit (Black wire). Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 18). No test procedures have been omitted.

18) Check VCRM PWR GND Circuit  Turn ignition off. Visually inspect VCRM PWR GND circuit (Black wire) between terminal No. 1 at VCRM connector and ground. VCRM circuit is grounded at a weld nut on right side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point. Also, lightly tap on VCRM to simulate road shock. An open circuit will be indicated by fan speed increasing to 100 percent (open circuit must be present for 5 seconds). If an open circuit is detected, isolate fault and repair as necessary. Clear continuous memory (Code 584 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, turn A/C and ignition off. Go to next step.

19) Check VCRM PWR GND Circuit (Cont.)  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 1 (Black wire) and No. 5 (Yellow wire) of VCRM connector. Observe test light, and shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point at right side of radiator support. Test light will go out if a fault is detected, indicating open circuit. If an open circuit is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

20) Continuous Memory Code 581  Continuous Memory Code 581 indicates that when cooling fan was activated, power to cooling fan circuit exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

Clear continuous memory. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 581 is present (hard code), go to next step. If Code 581 is not present (intermittent), go to step 24).

21) Check Cooling Fan Motor  Clear continuous memory. Disconnect cooling fan motor connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) self-test. If Code 581 is present, go to next step. If Code 581 is not present, replace cooling fan motor. Reconnect all connectors. Repeat QUICK TEST.

22) Check For Short To Ground In Cooling Fan Circuit  Turn ignition off. Ensure cooling fan motor connector is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in Light Blue wire. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 24). No test procedures have been omitted.

24) Check For Intermittent Short To Gnd. In Cooling Fan Ckt.  Turn ignition off. Visually inspect power-to-cooling fan circuit between terminal No. 2 (Light Blue wire) of VCRM connector and cooling fan motor connector. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power to cooling fan circuit between VCRM and cooling fan motor connector. A short to ground will be indicated by cooling fan turning off. Turn A/C and ignition off. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 581 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, go to next step.

25) Check VCRM Connector & Cooling Fan Circuit  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 2 (Light Blue wire) and No. 4 (Yellow wire) at VCRM connector. Test light should glow, but not at full brightness. Observe test light, and shake, wiggle and bend power-to-cooling fan circuit (Light Blue wire) near cooling fan. A short to ground is present if test light gets brighter. If a short to ground is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, disconnect and inspect cooling fan connector. Clean or repair connector as necessary. With test light still connected between terminals No. 2 and 4 of VCRM connector, observe test light and repeat power-to-cooling fan circuit wiggle test. If a short to ground is detected (test light gets brighter), isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.

30) Code 582  KOEO Code 582 indicates an open or short to power in cooling fan circuit. Following are possible causes for this fault.

If KOEO Code 587 is also present, repair fault causing KOEO Code 587 to set prior to continuing this test. See step 170). Ensure cooling fan was not turning during KOEO self-test. If fan was turning, feedback voltage could be sent to VCRM through power-to-cooling fan circuit, resulting in an invalid KOEO Code 582. Ensure engine is cooled down (cooling fan off). Ensure defroster and A/C are off. Turn ignition off. Check cooling fan. If cooling fan is on, go to step 35). If cooling fan is off, go to next step.

31) Check Power To Cooling Fan  Turn ignition off. Disconnect cooling fan connector. Start engine. Turn A/C on. Measure voltage between ground and power-to-cooling fan circuit (Light Blue wire) at cooling fan connector. If voltage is 6 volts or more, turn ignition off. Replace cooling fan. Repeat QUICK TEST. If voltage is less than 6 volts, go to next step.

32) Check Continuity Of Cooling Fan Circuit  Turn ignition off. Ensure cooling fan is disconnected. Measure resistance between ground circuit (Black wire) at cooling fan motor connector and negative battery terminal. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between cooling fan motor connector and ground. Reconnect cooling fan connector. Repeat QUICK TEST.

33) Check Continuity Of Cooling Fan Circuit (Cont.)  Turn ignition off. Ensure cooling fan is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan motor connector and terminals No. 2 and 3 of VCRM connector. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open in power-to-cooling fan circuit (Light Blue wire). Reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 33) to step 35). No test procedures have been omitted.

35) Check Power To Cooling Fan Circuit For Short To Power  Turn ignition off. Disconnect cooling fan motor connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between Light Blue wire at cooling fan connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Repeat QUICK TEST. If voltage is more than one volt, repair short to power in Light Blue wire. Reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 35) to step 40). No test procedures have been omitted.

40) Continuous Memory Code 578  Continuous Memory Code 578 indicates A/C Pressure (ACP) sensor VREF circuit is shorted to ground. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

Clear continuous memory. Start engine. Wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present (hard code), go to next step. If Code 578 is not present (intermittent), go to step 44).

41) Check ACP Sensor  Clear continuous memory. Turn ignition off. Disconnect ACP sensor connector. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present, go to next step. If Code 578 is not present, replace ACP sensor. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

42) Check ACP VREF Circuit For Short To Ground  Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP VREF circuit (Orange/Light Blue wire) at ACP sensor connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in ACP VREF circuit (Orange/Light Blue wire).

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 42) to step 44). No test procedures have been omitted.

44) Check For Intermittent Short To Ground In ACP VREF Circuit  Turn ignition off. Visually inspect ACP VREF circuit between terminal No. 20 (Orange/Light Blue wire) at VCRM connector and ACP sensor connector. Repair wiring as necessary. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Disconnect and inspect VCRM connector. Clean and repair connector as necessary. Connect test light between terminals No. 6 (Yellow wire) and No. 20 (Orange/Light Blue wire) at VCRM connector. Observe test light, and shake, wiggle and bend ACP VREF circuit between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated. Testing is complete. Reconnect all components.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 44) to step 50). No test procedures have been omitted.

50) Continuous Memory Code 579: Check ACP, VREF and ACP SIG RTN Circuits  Continuous Memory Code 579 indicates A/C Pressure (ACP) sensor did not detect a sufficient change in A/C system pressure when A/C system was turned on. This could be due to a problem in ACP sensor circuit or A/C system, and can be a hard fault or an intermittent condition. Following are possible causes for this fault.

If Continuous Memory Code 586 is present, repair fault causing code prior to continuing this test. See step 80). If Code 586 is not present, turn ignition off. Disconnect ACP sensor. Turn ignition on. Measure voltage between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. See Fig 2. If voltage is more than 6 volts, go to step 62). If voltage is less than 4 volts, go to step 63). If voltage is 4-6 volts, go to next step.

Fig 2: ACP Sensor Connector Terminal (XB2)
G93C28896

51) Check If A/C Clutch Engages  Turn ignition off. Reconnect ACP sensor. Start engine Turn A/C on and wait 30 seconds. If A/C clutch engages, go to next step. If A/C clutch does not engage go to step 57).

52) Clear And Attempt To Reset Code 579  Clear continuous memory. Start engine. Turn A/C on and wait until clutch engages. Turn A/C off and wait 5 seconds. Repeat turning A/C on and off 4 more times with each engagement lasting about 20 seconds. Turn A/C and engine off. Repeat Key On Engine Off (KOEO) self-test. If Code 579 is present, go to next step. If Code 579 is not present, ACP is now functioning. Either ACP is intermittent or marginal mechanical condition exists in A/C system, go to step 66).

53) Check A/C System Pressure & Pressure Change  Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. With A/C off, start engine. Observe A/C high pressure gauge reading, and turn A/C on. After 10 seconds, note pressure reading. High pressure should increase. If A/C high pressure gauge reading changes by more than 20 psi within 10 seconds of A/C clutch engagement, turn A/C and ignition off and go to next step. If A/C high pressure gauge reading does not change by more than 20 psi within 10 seconds of turning A/C on, check A/C system for mechanical fault. Service A/C system as necessary. Clear continuous memory. Attempt to reset Code 579 (see Code 52). Repeat QUICK TEST.

54) Check ACP Sensor Output  Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. Connect jumper wires and DVOM between ACP sensor connector halves as shown. See Fig 3. Start engine and observe voltage reading on DVOM. Turn A/C on and observe voltage reading for 10 seconds after clutch engages.

NOTE: Listen to A/C clutch to ensure clutch does not disengage during 10 seconds of testing. If clutch disengages, retest.

If ACP sensor voltage changes by more than .2 volt within 10 seconds of clutch engagement, sensor is operational. Remove jumper wires and go to next step. If ACP sensor voltage does not change by more than .2 volt within 10 seconds of turning A/C on, replace ACP sensor. Remove A/C system manifold gauge set. Remove jumper wires, and reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

Fig 3: Testing ACP Sensor (XB3)
G94A31609

55) Check ACP Circuit For Short To Ground  Turn ignition off. Ensure ACP sensor is disconnected. Disconnect VCRM connector. Measure resistance between ACP circuit terminal (Dark Green/White wire) on harness half of ACP sensor connector and negative battery terminal. Record resistance reading.

Measure resistance between ACP circuit terminal (Dark Green/White) and ACP SIG RTN circuit (Light Blue/Red wire) both on harness half of ACP sensor connector. If both resistance measurements are greater than 10,000 ohms, replace VCRM. Reconnect all components, clear continuous memory attempt to reset Code 579 and repeat quick test. If both measurements are not greater than 10,000 ohms, ACP or ACP SIG RTN circuit is shorted to ground. Repair shorted circuit, reconnect all components and clear continuous memory. Attempt to reset Code 579 and repeat quick test.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 55) to step 57). No test procedures have been omitted.

57) Check Voltage To A/C Clutch  Turn ignition off. Disconnect A/C cyclic pressure switch. Jumper the 2 terminals of A/C cyclic pressure switch connector together. Disconnect A/C clutch connector. Connect a test light between the 2 terminals of clutch connector. Start engine. Turn A/C on and wait 10 seconds. If test light does not glow, go to next step. If test light glows, circuit is okay. Check A/C system for mechanical problems. Reconnect all components, clear continuous memory. Attempt to reset Code 579 and repeat quick test.

58) Check Continuity Of ACP Circuit  Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP signal terminal at ACP connector and terminal No. 19 (Dark Green/White wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ACP circuit (Dark Green/White wire). Remove A/C system manifold gauge set. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

59) Check For Short To Power In ACP Circuit  Turn ignition off. Ensure ACP sensor and VCRM are disconnected. Turn ignition on. Measure voltage between ACP signal terminal (Dark Green/White wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in ACP circuit. Remove A/C system manifold gauge set. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

60) Check If Test Light Will Glow With ACP Circuit Grounded  Turn ignition off. Ensure ACP sensor is disconnected. Reconnect VCRM. Disconnect A/C cyclic pressure switch and jumper across the 2 terminals. Disconnect A/C clutch connector. Connect a test light between the 2 terminals on harness side of A/C clutch connector. Connect a jumper wire between ACP circuit (Dark Green White wire) and negative battery terminal. Start engine. Turn A/C on and wait 10 seconds. If test light glows, replace ACP sensor. Turn A/C off. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat quick test. If test light does not glow, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat quick test.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 60) to step 62). No test procedures have been omitted.

62) Check For Short To Power In ACP VREF Circuit  Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between ACP VREF terminal (Orange/Light Blue wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If voltage is more than one volt, repair short to power in ACP VREF circuit (Orange/Light Blue wire). Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

63) Check Continuity Of ACP SIG RTN & VREF Circuits  Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector and terminal No. 12 (Light Blue/Red wire) at VCRM connector. Record resistance reading. Measure resistance between ACP VREF terminal (Orange/Light Blue wire) at ACP sensor connector and terminal No. 20 (Orange/Light Blue wire) at VCRM connector. Record resistance reading. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ACP VREF circuit (Orange/Light Blue wire) or ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Start engine. Attempt to reset Code 579. Repeat QUICK TEST.

64) Check ACP SIG RTN Circuit For Short To VREF  Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) and ACP VREF terminal (Orange/Light Blue wire) at ACP connector. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, ACP SIG RTN circuit is shorted to ACP VREF circuit. Repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

65) Check For Short To Power In ACP SIG RTN Circuit  Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Turn ignition on. Measure voltage between ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If voltage is one volt or more, repair short to power in ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Attempt to reset Code 579. Repeat QUICK TEST.

66) Check A/C Cooling Performance  Check A/C system performance. If A/C system cools properly, go to step 67). If A/C system does not cool properly, Check mechanical condition of A/C system. If mechanical condition is okay, go to next step.

67) Check For Intermittent Open In ACP VREF & ACP SIG RTN Circuits  Turn A/C and ignition off. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Turn ignition on. Connect test light between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. Test light should turn on. If test light does not glow sufficiently, a DVOM may be used instead of test light to monitor 5-volt reference signal. Observe test light/DVOM, and shake, wiggle and bend ACP VREF and ACP SIG RTN circuits between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn off or DVOM voltage will drop, indicating open circuit. If open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If open circuit is not detected, go to next step.

68) Check ACP Signal Circuit For Intermittent Short  Turn ignition off. Ensure ACP sensor is disconnected. Connect test light or DVOM between ACP VREF terminal (Orange/Light Blue wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor connector. Test light should be off or DVOM reading should be zero volts. Observe test light/DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor connector and VCRM connector. Lightly tap on VCRM to simulate road shock. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

If a short to ground is not detected, remove test light/DVOM. Reconnect test light/DVOM between ACP SIG RTN terminal (Light Blue/Red wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor connector. Observe test light/DVOM, and repeat wiggle test of ACP signal circuit. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to power. If a short to power is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If short to power is not detected, go to next step.

69) Check ACP Signal Circuit For Intermittent Open  Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Using a DVOM, measure resistance of Dark Green/White wire between terminal No. 19 at VCRM connector and ACP signal terminal at ACP sensor connector. If resistance is 5 ohms or more, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is less than 5 ohms, observe DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor connector and VCRM connector. If a fault is detected, DVOM reading will show 5 ohms or more, indicating an open circuit. If an open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Reconnect all components.

70) Continuous Memory Code 585  Continuous Memory Code 585 indicates that power to A/C clutch exceeded normal current draw when A/C was turned on. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 585 is present, go to next step. If Code 585 is not present, go to step 74).

71) Check A/C Clutch  Clear continuous memory. Disconnect A/C clutch connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat Key On Engine Off (KOEO) self-test. Ignore Code 586 if set. If Code 585 is present, go to next step. If Code 585 is not present, check for short to ground in A/C clutch wiring circuit. Repair wiring as necessary. If wiring is okay, replace A/C clutch. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

72) Check For Short To Ground In A/C Clutch Circuit  Turn ignition off. Ensure A/C clutch is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Purple wire at A/C clutch connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 72) to step 74). No test procedures have been omitted.

74) Check For Intermittent Short To Ground In Power-To-A/C Clutch Circuit  Turn ignition off. Visually inspect Purple wire between A/C clutch and VCRM. Repair wiring as necessary. Start engine and turn A/C on. Shake, wiggle and bend Purple wire between A/C clutch connector and VCRM. A short to ground will be indicated by A/C clutch disengaging for other than normal A/C cycling pressure switch operation. If a short to ground is not detected, go to next step. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 585 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

75) Check A/C Clutch Circuit For Intermittent Short To Ground  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect a test light between terminals No. 4 (Yellow wire) and No. 14 (Purple wire) at VCRM connector. Observe test light, and shake, wiggle and bend Purple wire between A/C clutch connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 75) to step 80). No test procedures have been omitted.

80) Continuous Memory Code 586  Continuous Memory Code 586 indicates open or short to power in A/C clutch circuit. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

Clear continuous memory. Turn A/C and defroster off. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 586 is present, go to step 81). If Code 586 is not present, fault is intermittent. Go to step 85).

81) Check Short To Power In A/C Clutch Circuit  Turn ignition off. Disconnect A/C clutch connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Start engine and wait 15 seconds. Turn ignition off. Measure voltage at Purple wire between A/C clutch connector and negative battery terminal. If voltage is less than one volt, go to step 82). If voltage is one volt or more, repair short to power in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

82) Check Continuity Of A/C Clutch & VCRM A/C Ground Circuits  Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance of Purple wire between terminal No. 14 of VCRM connector and A/C clutch connector. Record resistance reading. Measure resistance between terminal No. 13 (Gray/White wire) and A/C clutch ground circuit (Black wire) at A/C clutch connector. Record resistance reading. If both resistance readings are less than 5 ohms, go to step 83). If resistance reading is 5 ohms or more in one or both circuits, repair open in circuit(s). Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

83) Check A/C Clutch Continuity  Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance between A/C clutch terminals. If resistance is less than 10 ohms, replace VCRM. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If resistance is 10 ohms or more, replace A/C clutch. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 83) to step 85). No test procedures have been omitted.

85) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits  Turn ignition off. Visually inspect power-to-A/C clutch circuit (terminal No. 14) and A/C clutch ground circuit (terminal No. 13) between VCRM and A/C clutch. Also check VCRM ground circuit (terminal No. 15) between VCRM connector and ground point at left side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. An open will be indicated by A/C clutch disengaging for other than normal cyclic pressure switch operation. If an open circuit is detected, isolate fault and repair as necessary. Turn A/C and ignition off. Repeat QUICK TEST. If an open is not detected, go to next step.

86) Check For Intermittent Short To Power In A/C Clutch Circuit  Ensure A/C is off. Turn ignition on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire) between VCRM and A/C clutch. A short to power will be indicated by A/C clutch engaging. If a short to power is detected, isolate fault and repair as necessary. Repeat QUICK TEST. If a short to power is not detected, go to step 87).

87) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits  Turn ignition off. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect test light between power-to-A/C clutch terminal (Purple wire) and A/C clutch ground terminal (Gray/White wire) at wiring harness side of A/C clutch connector. Start engine. Turn A/C on. Observe test light, and shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. Test light will turn off when a fault is detected, indicating an open circuit. If an open circuit is detected, isolate fault and repair as necessary. Reconnect all components. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, disconnect and inspect VCRM connector. Clean or repair connector as necessary. If connector is okay, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 87) to step 90). No test procedures have been omitted.
NOTE: Before proceeding with "No A/C" diagnostic procedures, check related fuses in fuse panel.

90) No A/C (With Code 111); Check Power At A/C Clutch  Turn ignition off. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at wiring harness side of A/C clutch connector. Turn A/C on. Start engine and wait 10 seconds. Observe test light. If test light glows, EEC-VI system is okay. Reconnect A/C clutch connector. Check A/C system for mechanical problems (eg. compressor or clutch coil). If test light is off, go to next step.

91) Check If PCM Is Receiving & Recognizing A/C Cyclic Pressure (ACCS) Input  Turn ignition off. Remove test light, and reconnect A/C clutch connector. Perform Key On Engine Off (KOEO) SELF-TEST. If KOEO Code 539 is present, PCM is receiving and recognizing ACCS input. Go to next step. If KOEO Code 539 is not present, PCM is not receiving or recognizing ACCS input. Go to step 96).

92) Check A/C Demand Signal Power At VCRM  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn A/C and ignition on. Measure voltage between terminal No. 9 (Black/Yellow wire) at VCRM connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in A/C demand signal circuit (Black/Yellow wire) between VCRM splice and PCM. Reconnect all components. Recheck system operation.

93) Check For Short To Ground In Wide Open Throttle A/C Cut Off (WAC) Circuit  Turn ignition off. Ensure VCRM is disconnected. Disconnect PCM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 11 (Pink/Yellow wire) at VCRM connector and negative battery terminal. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in WAC circuit. Reconnect all components. Recheck system operation.

94) Verify WAC Circuit Is Not Shorted To Ground In PCM  Turn ignition off. Disconnect PCM connector. Reconnect VCRM connector. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at wiring harness side of A/C clutch connector. Turn A/C and ignition on. If test light is on, replace PCM. Reconnect all components. Recheck system operation. If test light is off, replace VCRM. Reconnect all components. Recheck system operation.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 94) to step 96). No test procedures have been omitted.

96) Check For A/C Demand Signal Power At A/C Cyclic Pressure Switch  Turn ignition off. Disconnect A/C cyclic pressure switch. Turn A/C and ignition on. Measure voltage between A/C cyclic pressure switch connector (circuit to A/C-heater control panel) and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, ensure voltage is available to A/C-heater control panel, and A/C-heater control panel is functioning properly. If voltage to A/C-heater control panel is okay, repair open circuit between A/C-heater control panel and A/C cyclic pressure switch. Reconnect all components. Recheck system operation.

97) Check A/C Cyclic Pressure Switch Continuity  Turn ignition off. Disconnect A/C cyclic pressure switch. Check continuity between A/C cyclic switch terminals. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, check A/C system pressure and A/C cyclic pressure switch operation.

98) Check Continuity Between A/C Cyclic Pressure Switch & PCM  Turn ignition off. Ensure A/C cyclic pressure switch is disconnected. Install breakout box. Leave PCM disconnected. Measure resistance between test pin No. 10 at breakout box and circuit to PCM/VCRM at A/C cyclic pressure switch. If resistance is less than 5 ohms, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If resistance is 5 ohms or more, repair open in circuit between A/C cyclic pressure switch and PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 98) to step 100). No test procedures have been omitted.

100) Lack Of Power With A/C On  Verify Wide Open Throttle A/C Cut-Off (WAC) Is Able To Turn Off A/C Clutch. Start engine. Turn A/C on. Perform a brief Wide Open Throttle (WOT) and return to idle.A/C clutch should disengage during WOT, then a few seconds after returning to idle, A/C clutch should re-engage (click noise should be heard when clutch re-engages). Repeat test if necessary to verify results. If clicking noise cannot be heard, disconnect A/C clutch. Connect test light between power-to-A/C clutch circuit and ground circuit at wiring harness side of A/C clutch connector. Perform brief WOT. Test light should turn off during WOT, then turn on a few seconds after engine speed returns to idle. If A/C clutch or test light functions as specified, WAC circuit is okay. Test is complete. If A/C clutch or test light does not function as specified, go to next step.

101) Check WAC Circuit Wiring Harness Continuity  Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pin No. 54 at breakout box and terminal No. 11 (Pink/Yellow wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.

102) Check WAC Circuit For Short To Power  Turn ignition off. Ensure breakout box is still connected. Ensure VCRM and PCM are disconnected. Turn ignition on. Measure voltage between test pins No. 40 and 54 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.

103) Check VCRM WAC Circuitry  Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Reconnect VCRM connector. Turn ignition and A/C on. Connect a jumper wire to test pin No. 54 at breakout box. Listen to A/C clutch while briefly touching other end of jumper wire to test pin No. 40 at breakout box. Repeat procedure as necessary. If A/C clutch disengages and re-engages as jumper wire is connected and disconnected, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If A/C clutch does not disengage and re-engage as jumper wire is connected and disconnected, replace VCRM. Remove breakout box, and reconnect all components. Recheck system operation.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 103) to step 110). No test procedures have been omitted.

110) Code 556  KOEO Code 556 indicates a fuel pump primary circuit failure. Possible causes for this fault are an open or short to fuel pump circuit, damaged VCRM or damaged PCM. Check if engine will start. If engine starts, go to step 115). If engine does not start, go to next step.

111) Check Fuel Pump Circuit Continuity  Turn ignition off. Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM and VCRM disconnected. Measure resistance between test pin No. 22 at breakout box and terminal No. 18 (Light Blue/Orange wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

112) Check For Short To Power In Fuel Pump Circuit  Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Disconnect VCRM connector. Turn ignition on. Measure voltage between test pins No. 22 and 40 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

113) Check VCRM Fuel Pump Circuit  Turn ignition off. Ensure break-out box is still connected and PCM is disconnected. Reconnect VCRM connector. Connect jumper wire between test pins No. 22 and 40 at breakout box. Listen to fuel pump, and turn ignition on. If fuel pump runs, turn ignition off. Remove jumper wire. Replace PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If fuel pump does not run, turn ignition off. Remove jumper wire. Replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 113) to step 115). No test procedures have been omitted.

115) Check For Short To Ground In PCM  Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Turn ignition on. Listen to fuel pump. If fuel pump runs, turn ignition off and go to next step. If fuel pump does not run, turn ignition off. Replace PCM. Reconnect all components. Repeat QUICK TEST.

116) Check For Short To Ground In Fuel Pump Circuit  Turn ignition off. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pins No. 22 and 40 at breakout box. If resistance is more than 10,000 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 116) to step 120). No test procedures have been omitted.

120) Code 542  KOEO Code 542 indicates that one of the following has occurred.

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