DTC 78-1

DTC 78-1: VTM-4 Control Unit

NOTE: Before you troubleshoot, review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC.
3. Test-drive the vehicle, and check for DTCs with the HDS.

Is DTC 78-1 indicated?

YES - Go to step 4.

NO - Intermittent failure, the system is OK at this time.

4. Check the battery.

Is the specified battery installed, and is it fully charged?

YES - Go to step 5.

NO - Replace or charge the battery.

5. Watch the charging system indicator.

Does the charging system indicator come on with the ignition switch ON (II), and go off with the engine started?

YES - Go to step 6.

NO - Check the charging system.

6. Check for installation of any aftermarket CB or Ham radios which may cause an RF signal interference.

Is there an aftermarket radio installed?

YES - Disconnect the aftermarket radio, and retest.

NO - Check for poor connections or loose terminals at the VTM-4 control unit connectors. If the connections are OK, replace the VTM-4 control unit.