37-1

VTM-4 DTC Troubleshooting: 37-1, 38-1

DTC 37-1, 38-1: Engine RPM Signal Circuit

NOTE: Before you troubleshoot, review the general troubleshooting information. Initial Inspection and Diagnostic Overview

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

2. Make sure the HDS communicates with the vehicle and the VTM-4 control unit. If it doesn't, troubleshoot the DLC circuit. Testing and Inspection

3. Clear the DTC with the HDS.

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

Is DTCs 37-1 and/or 38-1 indicated?
YES - Go to step 5.

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


5. Check for DTC's in the PGM-FI DTCs indicated

Are there any PGM-FI DTCs indicated?
YES - Go to the indicated DTCs troubleshooting.

NO - Go to step 6.


6. Turn the ignition switch to LOCK (0).

7. Disconnect VTM-4 control unit connector A (22P).

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

9. Measure the voltage between VTM-4 control unit connector terminal A12 and body ground.





Is the voltage correct?
YES - Go to step 19.

NO - Go to step 10.






10. Turn the ignition switch to LOCK (0).

11. Jump the SCS line with the HDS.

12. Disconnect PCM connector A (44P).

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

14. Measure the voltage between VTM-4 control unit connector terminal A12 and body ground.

Is there voltage?
YES - Repair short to power in the wire between VTM-4 control unit connector terminal A12 and PCM connector terminal A33.

NO - Go to step 15.






15. Turn the ignition switch to LOCK (0).

16. Check for continuity between VTM-4 control unit connector terminal A12 and body ground.

Is there continuity?
YES - Repair short to ground in the wire between VTM-4 control unit connector terminal A12, and PCM connector terminal A33.

NO - Go to step 17.






17. Connect the VTM-4 control unit connector terminal A12 to body ground with a jumper wire.






18. Check for continuity between PCM connector terminal A33 and body ground.

Is there continuity?
YES - Go to step 19.

NO - Repair open in the wire between VTM-4 control unit connector terminal A12, and PCM connector terminal A33.






19. Check for poor connections or loose terminals at the VTM-4 control unit, and the PCM connectors. 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 then go to step 20.

20. Test-drive the vehicle, and watch the VTM-4 indicator.

Is DTCs 37-1 and/or 38-1 indicated?
YES - Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM Initial Inspection and Diagnostic Overview and recheck. If the symptom/indication goes away with the updated PCM, troubleshooting is complete. If the symptom/indication goes away a known-good PCM, replace the original PCM control unit. Service and Repair

NO - The system is OK at this time.