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 connector A (44P), then disconnect the HDS.
4. Measure resistance between ECM connector terminals A36 and A37.
Is there about 95 - 116 Ohm?
YES - Go to step 32.
NO - Go to step 5.
5. Disconnect the gauge control module (tach) 36P connector.
6. Disconnect the ABS modulator-control unit25P connector.
7. Disconnect SRS unit connector A (28P).
8. Disconnect EPS control unit connector D (28P).
9. Check for continuity between ECM connector terminals A36 and A37.
Is there continuity?
YES - Repair short in the wires between ECM connector terminals A36 and A37.
NO - Go to step 10.
10. Connect ECM connector terminal ASS to body ground with a jumper wire.
11. Check for continuity between gauge control module (tach) 36P connector terminal No. 1 and body ground.
Is there continuity?
YES - Go to step 12.
NO - Repair open in the wire between the ECM (ASS) and the gauge control module (tach).
12. Check for continuity between ABS modulator-control unit 25P connector terminal No. 1 and body ground.
Is there continuity?
YES - Go to step 13.
NO - Repair open in the wire between the ECM (ASS) and the ABS modulator-control unit.
13. Check for continuity between SRS unit connector A (28P) terminal No. 11 and body ground.
Is there continuity?
YES - Go to step 14.
NO - Repair open in the wire between the ECM (A36) and the SRS unit.
14. Check for continuity between EPS control unit connector D (28P) terminal No. 1 and body ground.
Is there continuity?
YES - Go to step 15.
NO - Repair open in the wire between the ECM (A36) and the EPS control unit.
15. Remove the jumper wire from ECM connector A (44P).
16. Connect ECM connector terminal A37 to body ground with a jumper wire.
17. Check for continuity between gauge control module (tach) 36P connector terminal No. 19 and body ground.
Is there continuity?
YES - Go to step 18.
NO - Repair open in the wire between the ECM (A37) and the gauge control module (tach).
18. Check for continuity between ABS modulator-control unit 25P connector terminal No. 17 and body ground.
Is there continuity?
YES - Go to step 19.
NO - Repair open in the wire between the ECM (A37) and the ABS modulator-control unit.
19. Check for continuity between SRS unit connector A (28P) terminal No. 12 and body ground.
Is there continuity?
YES - Go to step 20.
NO - Repair open in the wire between the ECM (A37) and the SRS unit.
20. Check for continuity between EPS control unit connector D (28P) terminal No. 15 and body ground.
Is there continuity?
YES - Go to step 21.
NO - Repair open in the wire between the ECM (A37) and the EPS control unit.
21. Reconnect the gauge control module (tach) 36P connector.
22. Measure resistance between ECM connector terminals ASS and A37.
Is there about 108 - 132 Ohm?
YES - Go to step 23.
NO - Substitute a known-good gauge control module (tach). If the HDS identifies the vehicle, replace the original gauge control module (tach).
23. Disconnect the gauge control module (tach) 36P connector.
24. Reconnect the ABS modulator-control unit25P connector.
25. Measure resistance between ECM connector terminals A36 and A37.
Is there about 2.34-2.86 kOhms?
YES - Go to step 26.
NO - Substitute a known-good ABS modulator-control unit. If the HDS identifies the vehicle, replace the original ABS modulator-control unit.
26. Disconnect the ABS modulator-control unit 25P connector.
27. Reconnect SRS unit connector A (28P).
28. Measure resistance between ECM connector terminals A36 and A37.
Is there about 2.34-2.86 kOhms?
YES - Go to step 29.
NO - Substitute a known-good SRS unit. If the HDS identifies the vehicle, replace the original SRS unit.
29. Disconnect SRS unit connector A (28P).
30. Reconnect EPS control unit connector D (28P).
31. Measure resistance between ECM connector terminals A36 and A37.
Is there about 2.34-2.86 kOhms?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away when a known-good ECM, replace the original ECM.
NO - Substitute a known-good EPS control unit. If the HDS identify the vehicle, replace the original EPS control unit.
32. Disconnect the gauge control module (tach) 36P connector.
33. Disconnect the ABS modulator-control unit 25P connector.
34. Disconnect SRS unit connector A (28P).
35. Disconnect EPS control unit connector D (28P).
36. Check for continuity between ECM connector terminal A36 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM connector terminal A36 and the gauge control module (tach), the ABS modulator-control unit, the SRS unit, the EPS control unit or the DLC.
NO - Go to step 37.
37. Check for continuity between ECM connector terminal A37 and body ground.
Is there continuity?
YES - Repair short in the wire between ECM connector terminal A37 and the gauge control module (tach), the ABS modulator-control unit, the SRS unit, the EPS control unit or the DLC.
NO - Go to step 38.
38. Reconnect all connectors.
39. Connect the HDS to the DLC.
40. Disconnect the gauge control module (tach) 36P connector.
41. 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 42.
42. Turn the ignition switch OFF.
43. Reconnect the gauge control module (tach) 36P connector.
44. Disconnect the ABS modulator-control unit 25P connector.
45. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the ABS modulator-control unit.
NO - Go to step 46.
46. Turn the ignition switch OFF.
47. Reconnect the ABS modulator-control unit 25P connector.
48. Disconnect SRS unit connector A (28P).
49. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the SRS unit.
NO - Go to step 50.
50. Turn the ignition switch OFF.
51. Reconnect SRS unit connector A (28P).
52. Disconnect EPS control unit connector D (28P).
53. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the EPS control unit.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.