F-CAN Circuit Troubleshooting
F-CAN Circuit TroubleshootingNOTE: Information marked with an asterisk (*) applies to the CANL line.
1. Turn the ignition switch OFF.
2. Jump the SCS line with the HDS.
3. Disconnect ECM/PCM connector A (44P), then disconnect the HDS.
4. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 99- 121 ohms?
YES - Go to step 26.
NO - Go to step 5.
5. Disconnect the gauge control module (tach) 36P connector.
6. Disconnect the ABS modulator-control unit 25P connector.
7. Disconnect SRS unit connector A (28P).
8. Check for continuity between ECM/PCM connector terminals A36 and A37.
Is there continuity?
YES - Repair short in the wires between ECM/PCM connector terminals A36 and A37*.
NO - Go to step 9.
9. Connect ECM/PCM connector terminal A36 to body ground with a jumper wire.
10. Check for continuity between gauge control module (tach) 36P connector terminal No.1 and body ground.
Is there continuity?
YES - Go to step 11.
NO - Repair open in the wire between the ECM/PCM (A36) and the gauge control module (tach).
11. Check for continuity between ABS modulator control unit 25P connector terminal No.1 and body ground.
Is there continuity?
YES - Go to step 12.
NO - Repair open in the wire between the ECM/PCM (A36) and the ABS modulator-control unit.
12. Check for continuity between SRS unit connector A (28P) terminal No.11 and body ground.
Is there continuity?
YES - Go to step 13.
NO - Repair open in the wire between the ECM/PCM (A36) and the SRS unit.
13. Remove the jumper wire from ECM/PCM connector A (44P).
14. Connect ECM/PCM connector terminal A37 to body ground with a jumper wire.
15. Check for continuity between gauge control module (tach) 36P connector terminal No.19 and body ground.
Is there continuity?
YES - Go to step 16.
NO - Repair open in the wire between the ECM/PCM (A37) and the gauge control module (tach).
16. Check for continuity between ABS modulator-control unit 25P connector terminal No.17 and body ground.
Is there continuity?
YES - Go to step 17.
NO - Repair open in the wire between the ECM/PCM (A37) and the ABS modulator-control unit.
17. Check for continuity between SRS unit connector A (28P) terminal No.12 and body ground.
Is there continuity?
YES - Go to step 18.
NO - Repair open in the wire between the ECM/PCM (A37) and the SRS unit.
18. Reconnect the gauge control module (tach) 36P connector.
19. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 108 - 132 ohms?
YES - Go to step 20.
NO - Substitute a known-good gauge control module (tach). If the HDS identifies the vehicle, replace the original gauge control module (tach).
20. Disconnect the gauge control module (tach) 36P connector.
21. Reconnect the ABS modulator-control unit 25P connector.
22. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 2.34 - 2.86 kohms?
YES - Go to step 23.
NO - Substitute a known-good ABS module at DTC control unit. If the HDS identifies the vehicle, replace the original ABS modulator-Control unit.
23. Disconnect the ABS modulator-control unit 25P connector.
24. Reconnect SRS unit connector A (28P).
25. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 2.34 - 2.86 kohms?
YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
NO - Substitute a known-good SRS unit. If the HDS identifies the vehicle, replace the original SRS unit.
26. Disconnect the gauge control module (tach) 36P connector.
27. Disconnect the ABS modulator-control unit 25P connector.
28. Disconnect SRS unit connector A (28P).
29. Check for continuity between ECM/PCM connector terminal A36 and body ground.
Is there continuity?
YES - Repair short in the wire between ECM/PCM connector terminal A36 and the gauge control module (tach), the ABS modulator-control unit, the SRS unit or the DLC.
NO - Go to step 30.
30. Check for continuity between ECM/PCM connector terminal A37 and body ground.
Is there continuity?
YES - Repair short in the wire between ECM/PCM connector terminal A37 and the gauge control module (tach), the ABS modulator-control unit, the SRS unit or the DLC.
NO - Go to step 31.
31. Reconnect all connectors.
32. Connect the HDS to the DLC.
33. Disconnect the gauge control module (tach) 36P connector.
34. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the gauge control module (tach).
NO - Go to step 35.
35. Turn the ignition switch OFF.
36. Reconnect the gauge control module (tach) 36P connector.
37. Disconnect the ABS modulator-control unit 25P connector.
38. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the ABS control unit.
NO - Go to step 39.
39. Turn the ignition switch OFF.
40. Reconnect the ABS modulator-control unit 25P connector.
41. Disconnect SRS unit connector A (28P).
42. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the SRS unit.
NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.