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:

Accelerator linkage.
Air cleaner assembly.
Air inlet tube.
Clean air tube and resonator.
Throttle body assembly.
IMRC actuator assembly.
Intake Manifold Runner Control (IMRC) assembly.
Wiring harness circuits (IMRC, IMRC MONITOR, SIG RTN, PWR GND and VPWR).
Powertrain Control Module (PCM).

Fig 1: Air Intake Circuit & Components Schematic

Fig 2: Identifying IMRC Wiring Harness Connector Terminals

Fig 3: Identifying Intake Manifold Tuning (IMT) Valve Vacuum Solenoid Wiring Harness Connector Terminals

HOT IDLE PID VALUES

Application

RPM PID

⁽¹⁾ IAC

A/T

720-770

20-44

M/T

700-750

19-43

⁽¹⁾	Idle air percent duty cycle.

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. Check for additional symptoms and repair as necessary. See TESTS W/O CODES - EEC-V article.

2) Check Accelerator Linkage

If linkage sticks, binds or grabs, go to next step. If linkage operation is okay, go to step 6).

3) Inspect Accelerator/Speed Control Cables

Turn ignition off. Disconnect accelerator and speed control cables from throttle body. Inspect cables for freedom of travel from accelerator pedal/speed control device to throttle body linkage cable connector. If cables move freely, go to next step. If cables do not move freely, repair as necessary.

4) Check Throttle Return Screw

Remove clean air tube from throttle body. Ensure no foreign material or debris is preventing throttle plate from rotating in fully closed position. Check throttle return screw. If throttle return screw is in contact with throttle linkage lever arm when throttle is fully closed, go to next step. If throttle screw is not as specified, replace throttle body.

5) Check Throttle Body

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 does not rotate freely, replace throttle body assembly. If throttle moves freely, fault cannot be duplicated or identified at this time. Check for additional symptoms and repair as necessary. See TESTS W/O CODES - EEC-V article.

6) Check Air Filter

Check air filter. Clean or replace as necessary. If air filter is okay, go to step 8).
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.

8) Check Related Engine Systems

If sent here from CIRCUIT TEST QA, go to next step. If not sent here from CIRCUIT TEST QA, ensure following engine systems are in good operating condition:
- Positive Crankcase Ventilation (PCV) system.
- Ignition system.
- Exhaust system.
- Engine cooling system. Ensure engine coolant temperature is more than 180°F (82°C).
- Fuel pressure. Fuel quality.
If systems are operating correctly, go to next step. If systems are not operating correctly, go to CIRCUIT TEST as indicated:
- Exhaust system: repair as necessary.
- Fuel pressure: CIRCUIT TEST HC .
- PCV system: CIRCUIT TEST HG .
- Engine cooling system: repair as necessary.

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 as necessary. If no faults are found, go to next step.

10) Check Idle Speed

Turn all accessories off. Start engine and warm to normal operating temperature. Using scan tool, select RPM PID and IAC PID, idle air percent duty cycle. See HOT IDLE PID VALUES table. If RPM and IAC PIDs are as specified, go to next step. If RPM AND IAC PIDS are not as specified, go to step 12).

11) Check Idle Control Response

Ensure engine is at normal operating temperature. Ensure electric cooling fan (if equipped) is off, but connector is not disconnected. With engine operating at idle, snap throttle wide open 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 engine speed does not fluctuate, air intake system is okay and testing is complete. Check for additional symptoms and repair as necessary. See TESTS W/O CODES - EEC-V article.

12) Check IAC Solenoid Function

Leave accessories off. With engine operating at idle, disconnect IAC solenoid connector. If engine speed does not change, replace IAC solenoid and clear Keep Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes. 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) 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 faults are present, replace throttle body and clear Keep Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes. If throttle body is okay, fault cannot be duplicated or identified at this time. Reinstall throttle body and check for additional symptoms and repair as necessary. See TESTS W/O CODES - EEC-V article.

14) Check IAC Circuit For Short To Ground

Leave accessories off and IAC solenoid disconnected. Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 83 (IAC) and test pin No. 51 or 103 (PWR GND) at the breakout box. If resistance is more than 10,000 ohms, replace PCM. If resistance is 10,000 ohms or less, repair short to ground.

15) DTC P1516, P1517, P1518 & P1519

DTCs P1516 and P1517 indicate control circuit failure. DTCs P1518 indicates IMRC stuck open. DTC P1519 indicates IMRC stuck closed. Possible causes are:
- Faulty vacuum hoses.
- Faulty vacuum solenoid.
- Faulty vacuum actuator.
- 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.
On models with electric IMRC system, visually inspect IMRC cables for correct routing. Ensure cable core wire has slack at IMRC housing and stop screw contacts lever. On models with vacuum operated IMRC system, ensure sensor linkage is attached and secure. With engine running, lever must contact closed plate stop screw. On all models, operate IMRC plates while checking for binding and sticking. If any faults are found, repair as necessary. If no faults are found, go to next step.

16) Check IMRC Function

If IMRC is vacuum controlled, start engine and allow to idle for 20 seconds. Turn ignition off. Turn ignition on. Using scan tool, access OUTPUT TEST MODE. Turn all outputs on. When IMRC is commanded on, lever(s) should rotate to full open position. 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 proceed as follows:
- With DTC P1516 and/or P1517, go to step 64).
- With DTC P1518, go to step 26).
- With DTC P1519, go to step 29).

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 P1516 and/or P1517, go to step 64).
- With DTC P1518, go to step 26).
- With DTC P1519, go to step 29).

18) Perform IMRC Mechanical Test

Turn ignition off. Disconnect cables from both left and right intake runners. Operate both levers while checking for binding or sticking. Feel for return spring tension. If any faults are found, repair as necessary. If no faults are found, proceed as follows:
- With DTC P1516 and/or P1517, go to step 64).
- With DTC P1518, go to step 26).
- With DTC P1519, go to step 29).

19) Verify IMRC Circuit Fault

Possible causes are:
- IMRC control circuit open or shorted to PWR GND or SIG RTN.
- VREF circuit open or shorted to IMRC control circuit.
- Faulty IMRC actuator.
- Faulty Powertrain Control Module (PCM).
Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select IMRCF PID. If PID value indicates YES, go to next step. If PID value indicates NO, fault is intermittent. Go to step 36).

20) Check IMRC Voltage

Turn ignition off. Disconnect IMRC actuator connector. Turn ignition on. Measure voltage between VPWR terminal at IMRC actuator wiring harness 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 VPWR circuit.

21) Check For Open Circuit

Measure voltage between SIG RTN terminal and VPWR terminal at IMRC actuator wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in SIG RTN circuit.

22) Check IMRC Circuit Driver For Short To Ground

Turn ignition off. Disconnect scan tool from DLC. Measure resistance between IMRC SIGNAL terminal at IMRC actuator wiring harness 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, go to step 39).

23) Check IMRC Circuit Driver For Short To Ground

Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure voltage between test pin No. 42 and test pin No. 51 or 103 (PWR GND) at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short circuit.

24) Check IMRC Circuit Driver For Open Circuit

Measure resistance between test pin No. 42 at breakout box and IMRC SIGNAL terminal at IMRC 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 IMRC SIGNAL circuit.

25) Verify PCM IMRC Driver

Reconnect IMRC actuator connector. Turn ignition on. Connect jumper wire between test pin No. 42 and test pin No. 51 or 103 at breakout box. If IMRC plates open, replace PCM. If IMRC plates do not open, replace IMRC actuator.

26) DTC P1518: Check IMRC MONITOR Circuit

DTC P1518 indicates low circuit voltage. Possible causes are:
- IMRC control circuit shorted.
- Faulty IMRC actuator.
- Faulty Powertrain Control Module (PCM).
Connect scan tool to DLC. Ensure IMRC plates are closed. If IMRC plates are open, go to step 20). Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select IMRCM PID from PID/DATA monitor menu. If PID voltage is more than 1.6 volts, go to step 34). If PID voltage is 1.6 volts or less, go to next step.

27) Check IMRC Monitor Circuit

Turn ignition off. Disconnect IMRC actuator connector. Turn ignition on. Using scan tool, select IMRCM PID. If PID voltage changed to more than 1.6 volts when IMRC actuator was disconnected, replace IMRC actuator. If PID voltage stayed at less than 1.6 volts, go to next step.

28) Check For Short To Ground

Turn ignition off. Disconnect PCM 104-pin connector. Disconnect scan tool from DLC. Measure resistance between IMRCM terminal at IMRC actuator wiring harness connector and negative battery terminal. Also, measure resistance between IMRCM terminal and SIG RTN terminal at IMRC actuator wiring harness connector. If both resistance readings are more than 10,000 ohms, replace PCM. If any resistance reading is 10,000 ohms or less, repair short to ground in IMRCM circuit.

29) DTC P1519

DTC P1519 indicates IMRC input is greater than expected. Possible causes are:
- IMRC circuit open.
- IMRC circuit shorted to ground or VREF.
- SIG RTN circuit open.
- Faulty IMRC actuator.
- Faulty Powertrain Control Module (PCM).
Turn ignition off. Disconnect IMRC actuator connector. Turn ignition on. Connect jumper wire between IMRCM terminal and SIG RTN terminal at IMRC actuator wiring harness connector. Using scan tool, select IMRCM PID from PID/DATA monitor menu.

NOTE: If scan tool communication error exists, remove jumper wire and go to step 38).

If PID voltage is less than .2 volt, remove jumper wire and go to step 40). If PID voltage is .2 volt or more, remove jumper wire and go to next step.

30) Check For Open In SIG RTN Circuit

Turn ignition off. Disconnect scan tool from DLC. Measure resistance between SIG RTN terminal at IMRC actuator wiring harness 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 SIG RTN circuit and go to step 33).

31) Check IMRCM Circuit Continuity

Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 8 (IMRCM) and IMRCM terminal at IMRC actuator 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) Check Circuit Operation

Turn ignition off. Reconnect all components. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access OUTPUT TEST MODE. Access IMRCM and IMRC PIDs. Connect DVOM between test pin No. 8 and test pin No. 51 or 103. Command outputs ON. IMRCM PID reading should be less than 1.6 volts (DVOM reading should be same) and IMRC PID value should indicate ON. If PID values are as specified, fault is intermittent, go to step 34). If PID values are not as specified, replace IMRC actuator and go to next step.

33) IMRC Verification Drive Cycle

Clear PCM memory. Using scan tool, select IMRC PID, IMRCM PID and RPM PID. Test drive vehicle with transmission in Overdrive. Complete 3 accelerations from a complete stop to a speed requiring engine speed of more than 3500 RPM. Watch for PID values to change. Stop vehicle. Repeat QUICK TEST and retrieve all DTCs. If any DTCs are present, go to appropriate CIRCUIT TEST . If no DTCs are present, testing is complete.

34) Wiggle Test

Turn ignition off. Disconnect IMRC actuator connector. Connect jumper wire between terminals IMRCM and SIG RTN at IMRC actuator wiring harness connector. Turn ignition on. Using scan tool, select IMRCM PID. Observe PID for signs of fault. A fault will be indicated by change in PID voltage from less than .2 volt to more than 1.6 volts. Wiggle wiring harness between IMRC actuator connector and PCM connector. If fault is indicated, isolate fault and repair as necessary. If no faults are indicated, remove jumper wire and go to next step.

35) Wiggle Test

Leave IMRC actuator disconnected. Turn ignition on. Using scan tool, select IMRCM PID. Observe PID for signs of fault. A fault will be indicated by change in PID voltage to less than 1.6 volt. Wiggle wiring harness between IMRC actuator connector and PCM connector. If fault is indicated, isolate fault and repair as necessary. If no faults are indicated, go to CIRCUIT TEST Z .

36) Intermittent Circuit Malfunction

Turn ignition off. Reconnect all components. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select OUTPUT TEST MODE. Select IMRCM and IMRC PIDs. If scan tool will not allow access to PIDs while in Output Test Mode, install Breakout Box (014-00950). Connect PCM to breakout box. Connect a DVOM between test pin No. 42 and test pin No. 51 or 103 at breakout box. Command outputs ON. IMRC PID should indicate ON and (DVOM should indicate less than one volt) and IMRCM PID should indicate less than 1.6 volts. Observe PID values for signs of fault. A fault will be indicated by sudden change in IMRCM PID voltage or in DVOM voltage reading. Wiggle wiring harness between IMRC actuator connector and PCM connector. If fault is indicated, isolate fault and repair as necessary. If no faults are indicated, go to next step.

37) Check For Intermittent Short To Ground

Turn ignition on. While observing IMRC plates, wiggle wiring harness between IMRC actuator connector and PCM connector. If IMRC plates move while wiggling harness, a possible short to ground in IMRC control circuit is indicated. Isolate fault and repair if necessary. If no faults are indicated, go to CIRCUIT TEST Z .

38) Check For Short To VREF Circuit

Turn ignition. Disconnect IMRC actuator connector. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pins No. 8 and 90 at breakout box. If resistance is more than 10,000 ohms, replace PCM. If resistance is 10,000 ohms or less, repair short between IMRCM and VREF circuit.

39) Check For Short To Ground

Turn ignition off. Disconnect IMRC actuator connector. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 42 and test pin No. 91 (SIG RTN) and 103 (PWR GND) at break. If both resistance readings are more than 10,000 ohms, replace PCM. If any resistance reading is 10,000 ohms or less, repair short to PWR GND or SIG RTN in IMRC control circuit.

40) Check IMRC Circuit

Turn ignition off. Reconnect all components. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access OUTPUT TEST MODE. Command all outputs ON. Observe IMRC lever(s). If lever(s) cycle open during output command, go to step 32). If levers do not cycle open during output command, go to step 20).
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 40) to step 64). No test procedures have been omitted.

64) Determine IMRC Fault Path

DTC P1516 or P1517 indicate IMRC plates open or closed time exceeded PCM program. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select IMRCM PID. Also select IMRC2M PID. If PID voltage is less than 3 volts, go to step 29). If PID voltage is 3 volts or more, go to step 26).

65) DTC P1549: Check IMT Valve & Vacuum Actuator Connection

This fault indicates IMTV circuit fault. Possible causes are:
- VPWR circuit open.
- Open or shorted signal circuit.
- Faulty IMT valve.
- Faulty Powertrain Control Module (PCM).
Turn ignition off. Check IMT valve system. Ensure wiring harness connector is installed properly. Repair as necessary. If no faults are found, go to next step.

66) Check PCM Driver Command

Start engine. Using scan tool, select IMTV PID from PID/DATA monitor menu. Observe PID value and increase engine speed to about 3500 RPM. PID value should indicate 100 percent then drop to 50 percent when engine RPM is more than 3500. If PID value is as specified, PCM driver command is okay. Go to next step. If PID value is not as specified, replace PCM.

67) Check IMT Valve Actuator Or Vacuum Solenoid VPWR Circuit For Open

Turn ignition off. Disconnect IMT valve actuator connector or IMT vacuum solenoid connector. See Fig 3. Measure resistance between chassis ground and VPWR terminal at IMT valve actuator/vacuum solenoid wiring harness connector. If voltage is more than 10.5 volts, go to step 69). If voltage is 10.5 volts or less, repair open in VREF circuit.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 67) to step 69). No test procedures have been omitted.

69) Check For Open Circuit

Turn ignition off. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 46 at breakout box and IMT VALVE SIGNAL terminal at IMT valve actuator/vacuum solenoid wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in IMT VALVE SIGNAL circuit.

70) Check IMT Valve Actuator Or Vacuum Solenoid Signal Circuit For Short To PWR GND

Measure resistance between test pin No. 46 and test pin No. 77 or 103 at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair IMT VALVE SIGNAL circuit short to PWR GND circuit.

71) Check IMT VALVE SIGNAL Circuit For Short To VPWR

Turn ignition on. Measure voltage between test pin No. 46 and test pin No. 77 or 103 at breakout box. If voltage is one volt or more, repair IMT VALVE SIGNAL circuit short to VPWR. If voltage is less than one volt, go to next step.

72) Check PCM Driver

Turn ignition off. Connect PCM to breakout box. Connect a DVOM between ground and VPWR terminal at IMT valve actuator/vacuum solenoid wiring harness connector. Turn ignition on. Voltage should be less than one volt. Using scan tool, access OUTPUT TEST MODE. Command all outputs ON. DVOM voltage reading should be more than 10.5 volts. If voltage is not as specified, replace PCM. If voltage is as specified, go to next step.

73) Check IMT Valve Shutter

Remove IMT valve. Check IMT valve shutter for damage. Rotate shutter and check for binding. Replace IMT valve as necessary. If IMT valve is okay, leave IMT valve disassembled.

74) Check IMT Valve Actuator

Reconnect IMT valve actuator connector. Turn ignition on. Using scan tool, access OUTPUT TEST MODE. Observe IMT valve shutter and command all outputs ON. If shutter rotates, no fault is indicated at this time. Go to CIRCUIT TEST Z . If shutter does not rotate, replace IMT valve actuator. Verify symptom is no longer present.

75) Check Manifold Vacuum

Reconnect IMT valve solenoid connector. Inspect IMT valve solenoid vacuum hoses for kinks, blockage, damage and proper routing. Repair as necessary. Disconnect vacuum supply hose (from intake manifold) at IMT valve solenoid. Install a vacuum gauge to disconnected vacuum supply hose. Start engine and allow to idle. If vacuum is more than 10 in. Hg, reconnect vacuum hose and go to next step. If vacuum is 10 in. Hg or less, repair vacuum source.

76) Check Vacuum between Vacuum Solenoid & IMT Valve

Disconnect vacuum supply hose (from solenoid) at IMT valve. Install a vacuum gauge to disconnected vacuum supply hose. Start engine and allow to idle. Note vacuum gauge reading. Increase engine speed to about 3500 RPM. Note vacuum gauge reading. If vacuum is zero in. Hg at idle and more than 10 in. Hg with engine speed at about 3500 RPM, go to step 73). If vacuum is not as specified, replace vacuum solenoid. Verify symptom is no longer present.

77) Check IMT Valve

Using a vacuum pump, apply about 10 in. Hg to IMT valve and observe IMT valve shutter. If shutter rotates 90 degrees with vacuum applied and returns to original position with vacuum released, fault is intermittent. Go to CIRCUIT TEST Z . If shutter does not operate as specified, replace IMT valve. Verify symptom is no longer present.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 77) to step 80). No test procedures have been omitted.

80) Check For Open Circuit

Turn ignition off. Disconnect vacuum solenoid connector. Turn ignition on. Measure voltage between chassis ground and VPWR terminal at vacuum solenoid wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit.

81) Check Voltage To Vacuum Actuators

Disconnect vacuum actuator connectors. Measure voltage between chassis ground and VPWR terminal at each vacuum actuator wiring harness connector. If both voltage readings are more than 10.5 volts, go to next step. If any voltage reading is 10.5 volts or less, repair open in VPWR circuit.

82) Check PCM Driver

Connect a DVOM between ground and VPWR terminal at vacuum solenoid wiring harness connector. Voltage should be less than one volt. Using scan tool, access OUTPUT TEST MODE. Command all outputs ON. DVOM voltage reading should be more that 10.5 volts. If voltage is not as specified, go to next step. If voltage is as specified, go to step 86).

83) Check For Short To PWR GND

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 42 and test pin No. 77 or 103 (PWR GND) at breakout box. 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 IMRC SIGNAL circuit.

84) Check For Short To VPWR

Turn ignition on. Measure voltage between test pin No. 42 and test pin No. 77 or 103 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to VPWR in IMRC SIGNAL circuit.

85) Check For Open In IMRC SIGNAL Circuit

Turn ignition off. Measure resistance between test pin No. 42 and IMRC SIGNAL terminal at vacuum solenoid wiring harness connector. If resistance is less than 5 ohms, no fault is indicated at this time. Reconnect all components and go to step 33). If resistance is 5 ohms or more, repair open in IMRC SIGNAL circuit. Go to step 33).

86) Check Vacuum To Vacuum Solenoid

Inspect vacuum solenoid hoses for kinks, blockage, damage and proper routing. Repair as necessary. Disconnect vacuum supply hose (from intake manifold) at vacuum solenoid. Install a vacuum gauge to disconnected vacuum supply hose. Start engine and allow to idle. If vacuum is more than 10 in. Hg, reconnect vacuum hose and go to next step. If vacuum is 10 in. Hg or less, repair vacuum source. Go to step 33).

87) Check Vacuum To Vacuum Actuators

Disconnect vacuum hose at vacuum solenoid (hose going to actuators). Install a vacuum gauge to vacuum solenoid. Start engine and allow to idle. Note vacuum gauge reading. Increase engine speed to about 3500 RPM. Note vacuum gauge reading. If vacuum is more than 10 in. Hg at idle and zero in. Hg with engine speed at about 3500 RPM, turn ignition off and go to next step. If vacuum is not as specified, replace vacuum solenoid. Verify symptom is no longer present.

88) Check For Open PWR GND Circuit

Turn ignition on. Measure voltage between PWR GND terminal and VPWR terminal at each vacuum actuator wiring harness connector. If both voltage readings are more than 10.5 volts, go to next step. If any voltage reading is 10.5 volts or less, repair open PWR GND circuit. Go to step 33).

89) Check For Short To VPWR

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Measure voltage between IMRC SIGNAL terminal and PWR GND terminal at each vacuum actuator wiring harness connector. If both voltage reading is less than one volt, go to next step. If any voltage reading is one volt or more, repair short to VPWR in IMRC SIGNAL circuit. Go to step 33).

90) Check For Short To PWR GND

Turn ignition off. Measure resistance between test pin No. 8 and test pin No. 77 or 103 at breakout box. Also, measure resistance between test pin No. 9 and test pin No. 77 or 103 at breakout box. If both resistance readings are more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, replace short to PWR GND. Go to step 33).

91) Check For Open Circuit

Measure resistance between test pin No. 8 at breakout box and IMRCM terminal at vacuum actuator (for right cylinder head) wiring harness connector. Also, measure resistance between test pin No. 9 at breakout box and IMRCM terminal at vacuum actuator (for left cylinder head) wiring harness connector. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading in 5 ohms or more, repair open circuit and go to step 33).

92) Check PCM Monitor Circuits

Connect PCM to breakout box. Turn ignition on. Using scan tool, select IMRCM and IMRC2M PIDs from PID/DATA monitor menu. Connect a jumper wire between test pins No. 8 and 103 at breakout box. IMRCM PID. voltage should be zero volts. Disconnect jumper wire at terminal No. 103 and connect jumper wire to terminal No. 97. IMRCM voltage should now be 2.5 volts. Connect a jumper wire between test pins No. 9 and 103 at breakout box. IMRC2M PID voltage reading should be zero volts. Disconnect jumper wire at terminal No. 103 and connect jumper wire to terminal No. 97. IMRC2M PID voltage should now be 2.5 volts (5 volts if checking at breakout box with a DVOM). If PID voltage readings are as specified, remove jumper wires and go to next step. If any PID voltage reading is not as specified, replace PCM. Go to step 33).

93) Check Signal Voltage

Reconnect vacuum actuator connectors and vacuum solenoid connector. Start engine and allow to idle. Note IMRCM and IMRC2M PID voltage readings. Increase engine speed to more than 3500 RPM. Again, note IMRCM and IMRC2M PID voltage readings. PID voltage readings should be more than 3 volts at idle and less than .5 volt with engine speed at more than 3500 RPM (voltage will be more than 6 volts at idle and less than on volt at 3500 RPM if checking at breakout box with a DVOM). If PID voltage readings are as specified, no fault is indicated at this time. Fault may be intermittent. Go to CIRCUIT TEST Z . If any PID voltage reading is not as specified, replace vacuum actuator that failed. Go to step 33).
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 93) to step 95). No test procedures have been omitted.

95) Perform IMRC Wiggle Test

Turn ignition off. Connect scan tool to DLC. Turn ignition on. Using scan tool, select IMRCM PID. Observe PID value while wiggling wiring harness between IMRC actuator connector and PCM. If PID value fluctuates, isolate fault and repair as necessary. If PID value does not fluctuate, replace PCM and go to step 33).