P1078
DTC Troubleshooting: P1078, P1078
DTC P1078:
IMT Valve Stuck in Low 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), or press the engine start/stop button to select the ON mode.
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 ECM/PCM.�
NO -
Go to step 4.
4. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
5. Disconnect the IMT actuator 5P connector.
6. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
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), or press the engine start/stop button to select the OFF mode.
9. Jump the SCS line with the HDS.
10. Disconnect ECM/PCM connector B (49P).
11. Check for continuity between ECM/PCM connector terminal B19 and body ground.
Is there continuity?
YES -
Repair short in the wire between the ECM/PCM(B19) and the IMT actuator, then go to step 24.
NO -
Go to step 31.
12. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
13. Jump the SCS line with the HDS.
14. Disconnect ECM/PCM connector C (49P).
15. Check for continuity between ECM/PCM connector terminal C48 and body ground.
Is there continuity?
YES -
Repair short in the wire between the ECM/PCM(C48) and the IMT actuator, then go to step 24.
NO -
Go to step 16.
16. Check for continuity between ECM/PCM connector terminal C49 and body ground.
Is there continuity?
YES -
Repair short in the wire between the ECM/PCM(C49) and the IMT actuator, then go to step 24.
NO -
Go to step 17.
17. Check for continuity between IMT actuator 5P connector terminal No. 5 and ECM/PCM connector terminal C48.
Is there continuity?
YES -
Go to step 18.
NO -
Repair open in the wire between the ECM/PCM(C48) and the IMT actuator, then go to step 24.
18. Check for continuity between IMT actuator 5P connector terminal No. 4 and ECM/PCM connector terminal C49.
Is there continuity?
YES -
Go to step 19.
NO -
Repair open in the wire between the ECM/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 upper cover, and repair the stuck 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), or press the engine start/stop button to select the ON mode.
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 32.
24. Reconnect all connectors.
25. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
26. Reset the ECM/PCM with the HDS.
27. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
28. Start the engine, and let it idle without load (A/T in P or N, M/T in neutral) until the radiator fan comes on.
29. Hold the engine speed at 4,000 rpm for 3 seconds or more, then let it idle.
30. Check for Pending or Confirmed 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 31.
31. Monitor the OBD STATUS for DTC P1078 in the DTCs MENU with the HDS.
Does the screen indicates PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 30, go to the indicated DTC's 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 28.
32. Reconnect all connectors.
33. Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM.
34. Start the engine, and let it idle without load (A/T in P or N, M/T in neutral) until the radiator fan comes on.
35. Hold the engine speed at 4,000 rpm for 3 seconds or more, then let it idle.
36. Check for Pending or Confirmed 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 34. If the ECM/PCM was substituted, go to step 1.
NO -
Go to step 37.
37. Monitor the OBD STATUS for DTC P1078 in the DTC's 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 Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 36, go to the indicated DTC's troubleshooting.�
NO -
If the screen indicated 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 34. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, go to step 34.