77-1

VTM-4 DTC Troubleshooting: 77-1

DTC 77-1:

PCM

NOTE:

- Before you troubleshoot, review the general troubleshooting information Initial Inspection and Diagnostic Overview.
- Check the fuel and emissions system DTCs. If there is a DTC, troubleshoot the indicated DTC first, then troubleshoot DTC 77-1.

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Test-drive the vehicle, and check for DTCs with the HDS.

Is DTC 77-1 indicated?

YES -

Go to step 4.

NO -

Intermittent failure, the system is OK at this time.

4. Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM.

5. Test-drive the vehicle, and check for DTCs with the HDS.

Is DTC 77-1 indicated?

YES -

Check for poor connections or loose terminals at the VTM-4 control unit. If the connections are OK, substitute a known-good VTM-4 control unit Service and Repair and recheck. If the symptom/indication goes away with the known-good VTM-4 control unit, replace the original VTM-4 control unit Service and Repair.

NO -

If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair.