DTC Troubleshooting
DTC P1077: IMT Valve Stuck in High RPM PositionNOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine. Hold the engine speed above 4,000 rpm.
4. Make sure the IMT VALVE CMD is OPEN in the DATA LIST with the HDS.
5. Check the IMT VALVE SW in the DATA LIST with the HDS.
Is CLOSED indicated?
YES - Go to step 6.
NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the IMT actuator and the ECM/PCM.
6. Let the engine idle, then turn the ignition switch OFF.
7. Disconnect the IMT actuator 5P connector.
8. Turn the ignition switch ON (II).
9. Measure voltage between IMT actuator 5P connector terminal No. 1 and body ground.
Is there about 5 V?
YES - Go to step 10.
NO - Repair open in the wire between the ECM/PCM (C14) and the IMT actuator, then go to step 27.
10. Measure voltage between IMT actuator 5P connector terminal No. 3 and body ground.
Is there about 5 V?
YES - Go to step 11.
NO - Go to step 16.
11. Turn the ignition switch OFF.
12. Jump the SCS line with the HDS.
13. Disconnect ECM/PCM connector C (22P).
14. Connect IMT actuator 5P connector terminal No. 2 to body ground with a jumper wire.
15. Check for continuity between ECM/PCM connector terminal C12 and body ground.
Is there continuity?
YES - Go to step 19.
NO - Repair open in the wire between the ECM/PCM (C12) and the IMT actuator, then go to step 27.
16. Disconnect ECM/PCM connector B (24P).
17. Connect IMT actuator 5P connector terminal No. 3 to body ground with a jumper wire.
18. Check for continuity between ECM/PCM connector terminal B11 and body ground.
Is there continuity?
YES - Go to step 34.
NO - Repair open in the wire between the ECM/PCM (B11) and the IMT actuator, then go to step 27.
19. Check for continuity between ECM/PCM connector terminal B4 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (B4) and the IMT actuator, then go to step 27.
NO - Go to step 20.
20. Connect IMT actuator 5P connector terminal No. 5 to body ground with a jumper wire.
21. Check for continuity between ECM/PCM connector terminal B4 and body ground.
Is there continuity?
YES - Go to step 22.
NO - Repair open in the wire between the ECM/PCM (B4) and the IMT actuator, then go to step 27.
22. Check for continuity between ECM/PCM connector terminal B3 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (B3) and the IMT actuator, then go to step 27.
NO - Go to step 23.
23. Connect IMT actuator 5P connector terminal No. 4 to body ground with a jumper wire.
24. Check for continuity between ECM/PCM connector terminal B3 and body ground.
Is there continuity?
YES - Go to step 25.
NO - Repair open in the wire between the ECM/PCM (B3) and the IMT actuator, go to step 27.
25. Remove the IMT actuator.
26. Move the IMT valve by hand.
Does it move smoothly?
YES - Substitute a known-good IMT actuator, then go to step 27 and recheck. If DTC P1078 is not indicated, replace the IMT actuator, then go to step 27. If DTC P1078 is indicated, then go to step 34.
NO - Remove the engine cover, and repair the stuck valve. If necessary, replace the intake manifold, then go to step 27.
27. Reconnect all connectors.
28. Turn the ignition switch ON (II).
29. Reset the ECM/PCM with the HDS.
30. Do the ECM/PCM idle learn procedure.
31. Start the engine. Hold the engine speed at 4,000 rpm for 10 seconds, then let it idle.
32. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1078 indicated?
YES - Check for poor connections or loose terminals at the IMT actuator and the ECM/PCM, then go to step 1.
NO - Go to step 33.
33. Monitor the OBD STATUS for DTC P1077 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 32, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 31.
34. Reconnect all connectors.
35. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
36. Start the engine. Hold the engine speed at 4,000 rpm for 10 seconds, then let it idle.
37. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1078 indicated?
YES - Check for poor connections or loose terminals at the IMT actuator and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 36. If the ECM/PCM was substituted, go to step 1.
NO - Go to step 38.
38. Monitor the OBD STATUS for DTC P1078 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. If any other Temporary DTCs or DTCs were indicated in step 37, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 36. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, go to step 36.