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Diagnostic Aids

Perform this test when instructed during QUICK TEST  or if directed by other test procedures. This test is used to diagnose the following:

Fig 1: Air Intake Circuit & Components Schematic
G95G12605
Fig 2: IMRC Connector Terminals
G95F35993
  1. Step 1) Confirm Drive Symptom  Test drive vehicle. Check for any of the following symptoms:
    • Accelerator pedal sticking or binding.
    • Hard start/long cranking.
    • Hesitation or stalls at idle.
    • Rough idle.
    • Lack of power.

    If symptom is present, go to next step. If symptom is not present, fault cannot be duplicated or identified at this time and testing is complete.

  2. Step 2) Check Accelerator Linkage  If linkage sticks, binds or grabs, go to next step. If linkage operation is okay, go to step 7).
  3. Step 3) Turn ignition off. Disconnect accelerator linkage from throttle body. Inspect cable for freedom of travel from accelerator pedal to throttle body linkage cable connector. If cable moves freely, go to next step. If cable does not move freely, repair or replace as necessary.
  4. Step 4) Check Throttle Return Screw  Leave ignition off and accelerator linkage disconnected from throttle body. Remove clean air tube from throttle body. Inspect clean air tube for dirt or contamination and repair as necessary. Check throttle return screw. If throttle return screw is in contact with throttle linkage lever arm when throttle is fully closed, go to step 6). If throttle screw is not as specified, place a .002" (.05 mm) feeler gauge between throttle return screw and lever arm. Turn screw until it contacts feeler gauge. Remove feeler gauge. Turn throttle adjust screw 1/2 turn clockwise and go to next step.
  5. Step 5) Check TP Sensor Range  Turn ignition off. Connect scan tester to DLC.Turn ignition on. Using scan tester, access TP PID. While observing TP PID, slowly move throttle from closed to open position. TP PID reading changes should be smooth while rotating throttle. At closed position, TP PID reading should be 0.66-1.20 volts (13-24%). If TP PID is as specified, remove scan tester and go to next step. If TP PID is not as specified, replace throttle body assembly.
  6. Step 6) Check Throttle Body  Turn ignition off. Disconnect cable from throttle body. Remove clean air tube. Snap throttle from wide open to closed position several times. Slowly cycle throttle from closed to wide open position. Check for freedom of travel especially during initial throttle opening. If throttle moves freely, fault cannot be duplicated or identified at this time and testing is complete. If throttle does not rotate freely, go to next step.
  7. Step 7) Check Air Filter  Check air filter and element. Clean or replace as necessary. If air filter and element are okay, go to next step.
  8. Step 8) Check Engine Operation  Ensure that the following engine systems are in good operating condition before continuing:
    • Engine cooling system.
    • Exhaust system.
    • Fuel pressure.
    • PCV system.

    If systems are operating correctly, go to next step. If systems are not operating correctly, go to CIRCUIT TEST indicated:

    • Exhaust system; CIRCUIT TEST HF.
    • Fuel pressure; CIRCUIT TEST HC.
    • PCV system; CIRCUIT TEST HG.
    • Engine cooling system; repair as necessary.
  9. Step 9) Check For Vacuum Leaks  Start engine and allow to idle. Inspect inlet air system from MAF sensor to intake manifold for cracks, loose connections or faulty gaskets. Inspect intake manifold, EGR diaphragm and vacuum hoses for leaks. Repair or replace as necessary. If no faults are found, go to next step.
  10. Step 10) Check Idle Speed  Turn all accessories off. Start engine and warm to normal operating temperature. Connect scan tester to DLC. Using scan tester, access IAC PID, idle air percent duty cycle. IAC PID reading should be approximately 20-45 percent at idle speed. If IAC PID values are correct, go to next step. If IAC PID values are not correct, go to step 12).
  11. Step 11) Check Idle Control Pressure  Leave accessories off. With engine operating at idle, goose throttle and return to idle position. If engine stalls or engine speed fluctuates excessively before returning to idle, go to next step. If engine does not stall or fluctuate, air intake system is okay and testing is complete.
  12. Step 12) Check IAC Solenoid Function  Leave accessories off. With engine operating at idle, disconnect IAC solenoid wiring harness connector. If engine speed does not change, replace IAC solenoid and clear Keep Alive Memory (KAM). If engine speed changes, proceed as follows:
    • For vehicles without fast idle symptom, go to next step.
    • For vehicles with fast idle symptom, go to step 14).
  13. Step 13) Check Throttle Body  Turn ignition off. Remove throttle body. With throttle fully closed, ensure light cannot be seen between throttle bore and plate. Snap throttle from wide open to closed position several times. Slowly cycle throttle from closed to wide open position. Check for freedom of travel especially during initial throttle opening. If throttle body is okay, fault cannot be duplicated or identified at this time and testing is complete. If faults are present, replace throttle body and clear Keep Alive Memory (KAM).
  14. Step 14) Check IAC Circuit For Short To Ground  Leave accessories off and IAC solenoid disconnected. Turn ignition off. Disconnect PCM 104-pin connector. Inspect pins for damage and repair if necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 83 (IAC) and test pins No. 51 and 103 (PWR GND) at the breakout box. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST .
  15. Step 15) DTC P1512, P1513, P1516, P1517, P1518, P1519, P1520, P1537 & P1538  DTCs P1516 and P1517 indicate control circuit failure. DTCs P1518, P1537 and P1538 indicate IMRC stuck open. DTCs P1512, P1513 and P1519 indicate IMRC stuck closed. DTC P1520 indicates control circuit failure. Possible causes are as follows:
    • Cables improperly routed, binding or seized.
    • Damaged or disconnected IMRC housing return springs.
    • Lever return stop obstructed or bent.
    • Lever wide open stop obstructed or bent.
    • IMRC actuator cable or gears seized.

    Visually inspect IMRC cables for correct routing. Ensure cable core wire has slack at IMRC housing and stop screw contacts plate. If adjustment is required, see INTAKE MANIFOLD RUNNER CONTROL (IMRC) in the ADJUSTMENTS - 2.0L article. Operate IMRC plates while checking for binding or sticking. If any faults are found, repair as necessary. If no faults are found, go to next step.

  16. Step 16) Check IMRC Function  If IMRC is vacuum controlled, start engine and allow to idle for 20 seconds. Turn ignition off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access Output Test Mode (OTM). Turn all outputs on. When IMRC is turned on, both levers should contact wide open stop. One or both levers should contact wide open stop (one lever being slightly off is acceptable). IRMC levers should cycle fully from closed to open position. If faults are present, go to next step. If no faults are present with DTC P1518, go to step 26). If no faults are present proceed as follows:
    • With DTC P1512 and/or P1513, go to step 41).
    • With DTC P1516 and/or P1517, go to step 64).
    • With DTC P1518, go to step 26).
    • With DTC P1519, go to step 29).
    • With DTC P1520, go to step 19).
    • With DTC P1537 and/or P1538, go to step 52).

    If DTC P1520 is present, service first before servicing other DTCs.

  17. Step 17) Check IMRC Operation  Start engine and allow to idle. Apply parking brake. Raise engine speed to more than 3500 RPM. When engine speed exceeds 3500 RPM, one or both levers should contact wide open stop (one lever being slightly off is acceptable). When engine speed drops to less than 3000 RPM, one or both levers should contact closed plate stop screw. If levers do not cycle, go to next step. If levers cycle as specified, proceed as follows:
    • With DTC P1512 and/or P1513, go to step 41).
    • With DTC P1516 and/or P1517, go to step 64).
    • With DTC P1518, go to step 26).
    • With DTC P1519, go to step 29).
    • With DTC P1520, go to step 19).
    • With DTC P1537 and/or P1538, go to step 52).

    If DTC P1520 is present, service first before servicing other DTCs.

  18. Step 18) Turn ignition off. Disconnect cables from IMRC assembly. Operate both levers while checking for binding or sticking. If any faults are found, repair as necessary. If no faults are found, proceed as follows:
    • With DTC P1512 and/or P1513, go to step 41).
    • With DTC P1516 and/or P1517, go to step 64).
    • With DTC P1518, go to step 26).
    • With DTC P1519, go to step 29).
    • With DTC P1520, go to step 19).
    • With DTC P1537 and/or P1538, go to step 52).

    If DTC P1520 is present, service first before servicing other DTCs.

  19. Step 19) DTC P1520  DTC P1520 indicates control circuit failure. Possible causes are as follows:
    • IMRC control circuit open or shorted to PWR GND or SIG RTN.
    • VREF circuit open or shorted to IMRC control circuit.
    • Faulty IMRC module.
    • Faulty Powertrain Control Module (PCM).

    Turn ignition off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access IMRCF PID. If IMRCF PID display is on, go to next step. If IMRCF PID display is not on, go to step 36).

  20. Step 20) Check IMRC Voltage  Turn ignition off. Disconnect IMRC module wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at IMRC wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in VPWR circuit. Clear PCM memory and repeat QUICK TEST .
  21. Step 21) Measure voltage between PWR GND terminal and VPWR terminal at IMRC wiring harness connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in PWR GND circuit. Clear PCM memory and repeat QUICK TEST .
  22. Step 22) Check IMRC Circuit Driver For Short To Ground  Turn ignition off. Measure resistance between IMRC terminal at wiring harness connector and negative battery terminal. If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, go to step 39).
  23. Step 23) Check IMRC Circuit Driver For Short To Ground  Leave ignition off and IMRC module disconnected. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure voltage between IMRC test pin and test pins No. 51 and 103 (PWR GND) at breakout box. If each measurement is one volt or more, go to next step. If either measurement is less than one volt, repair short circuit and repeat QUICK TEST .
    IMRC TEST PIN IDENTIFICATION

    Application Test Pin No.
    All Models 42
  24. Step 24) Check IMRC Circuit Driver For Open Circuit  Leave ignition off and IMRC module disconnected. Measure resistance between IMRC test at breakout box and IMRC terminal at wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
  25. Step 25) Verify PCM IMRC Driver  Reconnect IMRC module. Turn ignition on. Connect jumper wire between IMRC test pin and test pin No. 51 and 103 at breakout box. If IMRC plates open, replace PCM and repeat QUICK TEST. If IMRC plates do not open, replace IMRC module and repeat QUICK TEST .
  26. Step 26) DTC P1518: Check IMRC MONITOR Circuit  DTC P1518 indicates low circuit voltage. Possible causes are as follows:
    • IMRC control circuit shorted.
    • Faulty IMRC module.
    • Faulty Powertrain Control Module (PCM).

    Ensure IMRC plates are closed. If IMRC plates are open, go to step 20). Turn ignition off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access IMRCM PID. If PID voltage is 1.6 volts or more, go to step 34). If PID voltage is less than 1.6 volts, go to next step.

  27. Step 27) Turn ignition off. Disconnect IMRC module wiring harness connector. Turn ignition on. Using scan tester, access IMRCM PID. If PID voltage is 1.6 volts or more of what PID was with IMRC module disconnected, replace IMRC module. If PID voltage is less than 1.6 volts of what PID was with IMRC module disconnected, go to next step.
  28. Step 28) Turn ignition off. Leave IMRC module disconnected. Measure resistance between IMRC terminal at wiring harness connector and negative battery terminal. If resistance is 10,000 ohms or more, replace PCM. If resistance is less than 10,000 ohms, repair short in IMRCM circuit and repeat QUICK TEST .
  29. Step 29) DTC P1519  DTC P1519 indicates IMRC input is greater than expected. Possible causes are as follows:
    • IMRC circuit open.
    • IMRC circuit shorted to ground or VREF.
    • SIG RTN circuit open.
    • Faulty IMRC module.
    • Faulty Powertrain Control Module (PCM).

    If DTC P1520 is present, service before continuing. Leave ignition off and IMRC wiring harness connector disconnected. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Connect jumper wire between IMRC wiring harness connector terminals IMRCM and SIG RTN. Using scan tester, access IMRCM PID. If IMRCM PID voltage is 0.2 volt or less, go to step 40). If IMRCM PID voltage is more than 0.2 volt, remove jumper wire and go to next step.

  30. Step 30) Turn ignition off. Leave IMRC module disconnected. Measure resistance between SIG RTN terminal at IMRC wiring harness connector and negative battery terminal. If resistance is less than 55 ohms, go to next step. If resistance is more than 55 ohms, repair open in SIG RTN circuit and repeat QUICK TEST .
  31. Step 31) Check IMRCM Circuit Continuity  Leave ignition off and IMRC module disconnected. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 8 (IMRCM) and IMRCM terminal at wiring harness connector. If resistance is less than 5 ohms, replace PCM and go to step 33). If resistance is 5 ohms or more, repair open in IMRCM circuit and go to step 33).
  32. Step 32) DTC P1519: Check Circuit Operation  Turn ignition off. Reconnect all components. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access Output Test Mode (OTM). While in OTM, access IMRCM PID and IMRC PID voltage. Connect DVOM between test pin No. 8 and test pins No. 51 and 103. If PID voltage and DVOM voltage are less than 1.6 volts, go to step 34). If either voltage is more than 1.6 volts, replace IMRC module and go to next step.
  33. Step 33) IMRC Drive Cycle  Clear PCM memory. Using scan tester, access IMRC PID, IMRCM PID and RPM PID. Test drive vehicle with transmission in Overdrive. Complete 3 cycles from complete stop to speed requiring engine speed in excess of 3500 RPM. Stop vehicle. Repeat QUICK TEST  and retrieve all DTCs. If DTC 1519 is still present return to step 29). If any other DTCs are present, service as necessary. If no other DTCs are present, testing is complete.
  34. Step 34) Wiggle Test  Turn ignition off. Disconnect IMRC module. Connect jumper wire between IMRC wiring harness connector terminals IMRCM and SIG RTN. Turn ignition on. Using scan tester, access IMRCM PID. Observe PID for signs of fault. A fault will be indicated by change in PID voltage from less than 0.2 volt to more than 1.6 volts. Wiggle wiring harness between IMRC connector and PCM connector. If fault is indicated, isolate and repair as necessary. If no faults are indicated, remove jumper wire and go to next step.
  35. Step 35) Leave IMRC module disconnected. Turn ignition on. Using scan tester, access IMRCM PID. Observe PID for signs of fault. A fault will be indicated by change in PID voltage to more than 1.6 volt. Wiggle wiring harness between IMRC connector and PCM connector. If fault is indicated, isolate and repair as necessary. If no faults are indicated, go to CIRCUIT TEST Z.
  36. Step 36) Continuous Memory DTC P1520: Intermittent Circuit Malfunction  Turn ignition off. Reconnect all components. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access Output Test Mode (OTM). While in OTM, access IMRCM PID and IMRC PID. Connect DVOM between test IRMC test pin and test pins No. 51 and 103. Command outputs on. Observe PID for signs of fault. A fault will be indicated by sudden change in PID voltage. Wiggle wiring harness between IMRC connector and PCM connector. If fault is indicated, isolate and repair as necessary. If no faults are indicated, go to next step.
  37. Step 37) Turn ignition on. While observing IMRC plates, wiggle wiring harness between IMRC module and PCM connector. If IMRC plates open while wiggling harness, fault is indicated. Isolate and repair as necessary. If no faults are indicated, go to CIRCUIT TEST Z.
  38. Step 38) Leave ignition off and IMRC disconnected. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 8 (IMRCM) and 90 (VREF) at breakout box. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST . If resistance is less than 10,000 ohms, repair short between IMRCM and VREF circuit.
  39. Step 39) Leave ignition off and IMRC disconnected. Measure resistance between IMRC test pin and test pins No. 51 and 103 (PWR GND) at breakout box. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST . If resistance is less than 10,000 ohms, repair short to ground in PWR GND in IMRC control circuit.
  40. Step 40) Check IMRC Circuit  Turn ignition off. Reconnect all components. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access Output Test Mode (OTM). While in OTM, turn all outputs on. Observe IMRC levers. If levers cycle open during output command, go to step 32). If levers do not cycle open during output command, go to step 20).
  41. Step 41) Check IMRC Actuator  DTC P1512, P1513, P1516 and P1517 indicates IMRC plates are stuck open. Possible causes are as follows:
    • Broken or restricted vacuum hoses.
    • IMRC circuit open.
    • IMRC circuit shorted to ground or VREF.
    • SIG RTN circuit open.
    • Faulty IMRC module.
    • Faulty Powertrain Control Module (PCM).

    For vacuum operated systems, start engine and allow to idle for 20 seconds. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access IMRCM PID and IMRC2M PID. Manually rotate IMRC levers. If PID voltage is 3.0 volts or more as levers are rotated, go to step 47). If PID voltage is not as specified, go to next step.

  42. Step 42) Check IMRC Monitor Signal  For vacuum operated systems, start engine and allow to idle for 20 seconds. With scan tester connected to DLC, turn ignition on. Using scan tester, access IMRCM PID and IMRC2M PID. Disconnect both IMRC actuator wiring harness connectors. Using jumper wire, connect IMRCM and IMRC2M connector terminals to ground. If PID voltage change is less than 1.0 volt, go to next step. If PID voltage change is 1.0 volt or more, go to step 44).
  43. Step 43) Turn ignition off. Leave both IMRC actuator wiring harness connectors disconnected. Measure resistance between IMRC terminal and PWR GND terminal at actuator. Measure resistance between IMRC terminal and VPWR terminal at actuator. If resistance is not 100-10,000 ohms, replace IMRC actuator and go to step 33). If resistance is 100-10,000 ohms, fault cannot be duplicated at this time. Go to CIRCUIT TEST Z.
  44. Step 44) Leave ignition off and both IMRC actuator wiring harness connectors disconnected. Measure resistance between PWR GND terminal at actuator and chassis ground. If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, repair open circuit go to step 33).
  45. Step 45) Leave ignition off and both IMRC actuator wiring harness connectors disconnected. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Connect negative lead of DVOM to test pin No. 77 or 104 (PWR GND) at breakout box. Check voltage at test pin No. 8. and 9. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair circuit short to VPWR and go to step 33).
  46. Step 46) Turn ignition off. Leave both IMRC actuator wiring harness connectors disconnected. Measure resistance between IMRCM terminal at actuator and test pin No. 8 and 9. If resistance is less than 5 ohms, replace PCM and go to step 33). If resistance is 5 ohms or more, repair open in IMRCM circuit and go to step 33).
  47. Step 47) Connect scan tester to DLC. Turn ignition on. Using scan tester, access IMRCM PID and IMRC2M PID. Observe PID values. Start engine and allow to idle. Access IMRCM PID and IMRC2M PID. If PID values change, fault is intermittent and cannot be duplicated at this time. Go to CIRCUIT TEST Z. If PID values do not change, go to next step.
  48. Step 48) Turn ignition off. Disconnect left IMRC actuator vacuum hose. Ensure hose is not damaged or restricted. Connect vacuum hose to vacuum gauge. Start engine and allow to idle. If vacuum reading is less than 10 in. Hg, go to next step. If vacuum reading is 10 in. Hg or more, replace IMRC actuator and go to step 33).
  49. Step 49) Turn ignition off. Disconnect right IMRC actuator vacuum hose. Ensure hose is not damaged or restricted. Connect vacuum hose to vacuum gauge. Start engine and allow to idle. If vacuum reading is less than 10 in. Hg, go to next step. If vacuum reading is 10 in. Hg or more, replace IMRC actuator and go to step 33).
  50. Step 50) Check IMRC Circuit To PCM  Turn ignition off. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 42 and test pins 77 and 103 at breakout box. If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, repair IMRCM circuit short to PWR GND and go to step 33).
  51. Step 51) Check IMRC Circuit For Short  Turn ignition off. Connect PCM to breakout box. With vacuum gauge connected to IMRC actuator vacuum hose, start engine and allow to idle. Connect jumper wire between test pin No. 42 and test pin 77 or 103 (PWR GND) at breakout box. If vacuum reading is less than 10 in. Hg, replace PCM and go to step 33). If vacuum reading is 10 in. Hg or more, replace IMRC actuator and go to step 33).
  52. Step 52) Check IMRC Actuator  DTC P1516, P1517, P1537 and P1538 indicates IMRC plates are stuck open. Possible causes are as follows:
    • Broken or restricted vacuum hoses.
    • IMRC circuit open.
    • IMRC circuit shorted to ground or VREF.
    • SIG RTN circuit open.
    • Faulty IMRC module.
    • Faulty Powertrain Control Module (PCM).

    For vacuum operated systems, start engine and allow to idle for 20 seconds. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access IMRCM PID. Access IMRC2M PID. If PID voltage is less than 1.0 volt, go to next step. If PID voltage is 1.0 volts or more, fault is intermittent. Go to step 54).

  53. Step 53) Check IMRC PID Reading  For vacuum operated systems, start engine and allow to idle for 20 seconds. With ignition on, use scan tester to access IMRCM PID. Access IMRC2M PID. Proceed as follows:
    • Disconnect left IMRC actuator connector and note PID voltage.
    • Disconnect right IMRC actuator connector and note PID voltage.
    • Reconnect right IMRC actuator connector and note PID voltage.
    • Reconnect left IMRC actuator connector and note PID voltage.

    If PID values increase is 1.0 volt or more, isolate and replace defective IMRC actuator. Go to step 33). If PID values do not increase more than 1.0 volt, go to step 55).

  54. Step 54) Wiggle Test  For vacuum operated systems, start engine and allow to idle for 20 seconds. After about 30 seconds, vacuum will bleed off and PID values will change. Restart engine if necessary. With ignition on, use scan tester to access IMRCM PID. Access IMRC2M PID. Turn ignition to ON position. Wiggle IMRC wiring harness between actuator and PCM. Observe PID for signs of fault. A fault will be indicated by a sudden drop in PID voltage. Wiggle wiring harness between IMRC connector and PCM connector. If fault is indicated, isolate and repair as necessary. Go to step 33). If no faults are indicated, fault cannot be duplicated at this time. Go to CIRCUIT TEST Z.
  55. Step 55) Check IMRC Vacuum Supply  Turn ignition off. Disconnect IMRC actuator vacuum hose. Ensure hose is not damaged or restricted. Connect vacuum hose to vacuum gauge. Start engine and allow to idle. If vacuum reading is more than 10 in. Hg, go to next step. If vacuum reading is 10 in. Hg or less, replace IMRC actuator and go to step 33).
  56. Step 56) Turn ignition off. Disconnect left IMRC actuator vacuum hose. Ensure hose is not damaged or restricted. Connect vacuum hose to vacuum gauge. Start engine and allow to idle. If vacuum reading is less than 10 in. Hg, go to next step. If vacuum reading is 10 in. Hg or more, go to step 60).
  57. Step 57) Check VPWR Circuit  Turn ignition off. Disconnect IMRC actuator wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal of connector and chassis ground. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open circuit and go to step 33).
  58. Step 58) Check IMRC Circuit For Open  Turn ignition off. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 42 at breakout box and IMRC terminal at actuator wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in IMRCM circuit and go to step 33).
  59. Step 59) Check IMRC Circuit To PCM  Turn ignition on. Measure voltage between test pin No. 42 and test pins 77 and 103 at breakout box. If voltage is 10.5 volts or more, repair IMRC circuit short to VREF or VPWR. If voltage is less than 10.5 volts, replace IMRC vacuum actuator. Go to step 33).
  60. Step 60) Check VPWR Circuit  Turn ignition off. Disconnect both IMRC sensor wiring harness connectors. Turn ignition on. Measure voltage between VPWR terminal of connector and chassis ground. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in VPWR circuit and go to step 33).
  61. Step 61) IMRCM Circuit Check For Short To Ground  Turn ignition off. Leave both IMRC sensor wiring harness connectors disconnected. Disconnect scan tester from DLC. Measure resistance between IMRCM terminal at both connectors and chassis ground. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, go to step 63).
  62. Step 62) IMRC Sensor Check  Leave ignition off and both IMRC sensor wiring harness connectors disconnected. Measure resistance between IMRC terminal and PWR GND terminal at both sensors. If resistance is not 1000-20,000 ohms, replace IMRC sensor and, go to step 33). If resistance is 1000-20,000 ohms, fault is intermittent and cannot be duplicated at this time. Go to CIRCUIT TEST Z.
  63. Step 63) Check PCM For Internal Short  Leave ignition off and both IMRC sensor wiring harness connectors disconnected. Measure resistance between test pin No. 8 and test pins 77 and 103 at breakout box. If resistance is 10,000 ohms or more, replace PCM and go to step 33). If resistance is less than 10,000 ohms, repair circuit short to PWR GND and go to step 33).
  64. Step 64) Determine IMRC Fault Path  DTC P1516 or P1517 indicate IMRC plates are open or closed time exceeded PCM program. For vacuum operated systems, start engine and allow to idle for 20 seconds. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access IMRCM PID. Access IMRC2M PID. If PID voltage is less than 3.0 volts, go to step 26) for electronic controlled systems or step 55) for vacuum controlled systems. If PID voltage is 3.0 volts or more, go to step 29) for electronic controlled systems or step 41) for vacuum controlled systems.
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