DTC 38-1
DTC 38-1: Engine RPM Signal Circuit1. Clear the DTCs.
2. Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on?
YES-Go to step 3.
NO-The system is OK at this time.
3. Watch the MIL.
Does the MIL come on?
YES-Check the fuel and emission system for DTCs.
NO-Go to step 4.
4. Disconnect connector A (22P) from the VTM-4 control unit.
5. Measure the voltage between the A12 terminal and body ground with the engine running.
Is the voltage correct?
YES-Go to step 13.
NO-Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect PCM connector A (44P) and gauge assembly connector B (22P).
8. Turn the ignition switch ON (II).
9. Measure the voltage between the A12 terminal of the VTM-4 control unit and body ground.
Is there voltage?
YES-Repair short to power in the wire between the A12 terminal of the VTM-4 control unit and the A28 terminal of the PCM.
NO-Go to step 10.
10. Turn the ignition switch OFF.
11. Check for continuity between the A12 terminal of the VTM-4 control unit and body ground.
Is there continuity?
YES-Repair short to ground in the wire between the A12 terminal of the VTM-4 control unit, the A28 terminal of the PCM, and the B8 terminal of the gauge assembly.
NO-Go to step 12.
12. Connect the A12 terminal of the VTM-4 control unit connector A (22P) to body ground with the jumper wire, then check for continuity between the A28 terminal of the PCM, the B8 terminal of the gauge assembly, and body ground.
Is there continuity?
YES-Go to step 13.
NO-Repair open in the wire between the A12 terminal of the VTM-4 control unit, the A28 terminal of the PCM, and the B8 terminal of the gauge assembly.
13. Check for loose terminal fit in the VTM-4 control unit, PCM connectors, and the gauge assembly connectors. If it is normal, replace the VTM-4 control unit. Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on?
YES-Replace the PCM or gauge assembly.
NO-The system is OK at this time.