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.
DTCs P1516 and P1517 indicate control circuit failure. DTCs P1518, P1520, P1537 and P1538 indicate IMRC stuck open. DTC P1512, P1513 & 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).
Mar 15, 2010 at 10:11 AM
