DTC Troubleshooting
DTC Troubleshooting: P1077
DTC P1077:
IMT Valve Stuck in High RPM Position
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Do the IMT TEST in the INSPECTION MENU with the HDS.
Is the result OK?
YES -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the IMT actuator and the PCM.�
NO -
Go to step 4.
4. Turn the ignition switch to LOCK (0).
5. Disconnect the IMT actuator 5P connector.
6. Turn the ignition switch to ON (II).
7. Check the IMT VALVE SW in the DATA LIST with the HDS.
Is CLOSE indicated?
YES -
Go to step 12.
NO -
Go to step 8.
8. Turn the ignition switch to LOCK (0).
9. Jump the SCS line with the HDS.
10. Disconnect PCM connector B (49P).
11. Check for continuity between PCM connector terminal B19 and body ground.
Is there continuity?
YES -
Repair a short in the wire between the PCM(B19) and the IMT actuator, then go to step 24.
NO -
Go to step 31.
12. Turn the ignition switch to LOCK (0).
13. Jump the SCS line with the HDS.
14. Disconnect PCM connector C (49P).
15. Check for continuity between PCM connector terminal C48 and body ground.
Is there continuity?
YES -
Repair a short in the wire between the PCM(C48) and the IMT actuator, then go to step 24.
NO -
Go to step 16.
16. Check for continuity between PCM connector terminal C49 and body ground.
Is there continuity?
YES -
Repair a short in the wire between the PCM(C49) and the IMT actuator, then go to step 24.
NO -
Go to step 17.
17. Check for continuity between PCM connector terminal C48 and IMT actuator 5P connector terminal No. 5.
Is there continuity?
YES -
Go to step 18.
NO -
Repair an open in the wire between the PCM(C48) and the IMT actuator, then go to step 24.
18. Check for continuity between PCM connector terminal C49 and IMT actuator 5P connector terminal No. 4.
Is there continuity?
YES -
Go to step 19.
NO -
Repair an open in the wire between the PCM(C49) and the IMT actuator, then go to step 24.
19. Remove the IMT actuator Service and Repair.
20. Move the IMT valve by hand.
Does it move smoothly?
YES -
Go to step 21.
NO -
Remove the intake manifold cover, and repair the stick valve. If needed, replace the intake manifold, then go to step 24.
21. Substitute a known-good IMT actuator Service and Repair.
22. Turn the ignition switch to ON (II).
23. Do the IMT TEST in the INSPECTION MENU with the HDS.
Is the result OK?
YES -
Replace the original IMT actuator Service and Repair, then go to step 24.
NO -
Go to step 31.
24. Reconnect all connectors.
25. Turn the ignition switch to ON (II).
26. Reset the PCM with the HDS.
27. Do the PCM idle learn procedure PCM Idle Learn Procedure.
28. Start the engine, and let it idle without load (in P or N) until the radiator fan comes on.
29. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P1077 indicated?
YES -
Check for poor connections or loose terminals at the IMT actuator and the PCM, then go to step 1.
NO -
Go to step 30.
30. Monitor the OBD STATUS for DTC P1077 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 29, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.
31. Reconnect all connectors.
32. Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM.
33. Start the engine, and let it idle without load (in P or N) until the radiator fan comes on.
34. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P1077 indicated?
YES -
Check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 33. If the PCM was substituted, go to step 1.
NO -
Go to step 35.
35. Monitor the OBD STATUS for DTC P1077 in the DTC's MENU with the HDS.
Does the HDS indicate PASSED?
YES -
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 34, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicated FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 33. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 33.