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 (95-116 ohms (with TPMS))?
YES - Go to step 33.
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. With TPMS: Disconnect TPMS control unit 20P connector.
9. 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 10.
10. Connect ECM/PCM connector terminal A36 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/PCM (A36) 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/PCM (A36) 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 -
- With TPMS: Go to step 14.
- Without TPMS: Go to step 15.
NO - Repair open in the wire between the ECM/PCM (A36) and the SRS unit.
14. Check for continuity between TPMS control unit 20P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 15.
NO - Repair open in the wire between the ECM/PCM (A36) and the TPMS control unit.
15. Remove the jumper wire from ECM/PCM connector A (44P).
16. Connect ECM/PCM 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/PCM (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/PCM (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
- With TPMS: Go to step 20.
- Without TPMS: Go to step 21.
NO - Repair open in the wire between the ECM/PCM (A37) and the SRS unit.
20. Check for continuity between TPMS control unit 20P connector terminal No. 11 and body ground.
Is there continuity?
YES - Go to step 21.
NO - Repair open in the wire between the ECM/PCM (A37) and the TPMS control unit.
21. Remove the jumper wire from ECM/PCM connector A(44P).
22. Reconnect the gauge control module (tach) 36P connector.
23. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 108-132 ohms?
YES - Go to step 24.
NO - Substitute a known-good gauge control module (tach). If the HDS identifies the vehicle, replace the original gauge control module (tach).
24. Disconnect the gauge control module (tach) 36P connector.
25. Reconnect the ABS modulator control unit 25P connector.
26. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 2.34-2.86 kohms?
YES - Go to step 27.
NO - Substitute a known-good ABS modulator control unit. If the HDS identifies the vehicle, replace the original ABS modulator-control unit.
27. Disconnect the ABS modulator control unit 25P connector.
28. Reconnect SRS unit connector A (28P).
29. Measure resistance between ECM/PCM connector terminals A36 and A37.
Is there about 2.34-2.86 kohms?
YES -
- With TPMS: Go to step 30.
- Without TPMS: 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.
30. Disconnect SRS unit connector A (28P).
31. Reconnect TPMS control unit 20P connector.
32. 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 TPMS control unit. If the HDS identifies the vehicle, replace the original TPMS control unit.
33. Disconnect the gauge control module (tach) 36P connector.
34. Disconnect the ABS modulator control unit 25P connector.
35. Disconnect SRS unit connector A (28P).
36. With TPMS: Disconnect the TPMS control unit 20P connector.
37. 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, the TPMS control unit (with TPMS), or the DLC.
NO - Go to step 38.
38. 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, the TPMS control unit (with TPMS), or the DLC.
NO - Go to step 39.
39. Reconnect all connectors.
40. Connect the HDS to the DLC.
41. Disconnect the gauge control module (tach) 36P connector.
42. 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 43.
43. Turn the ignition switch OFF.
44. Reconnect the gauge control module (tach) 36P connector.
45. Disconnect the ABS modulator-control unit 25P connector.
46. 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 47.
47. Turn the ignition switch OFF.
48. Reconnect the ABS modulator-control unit 25P connector.
49. Disconnect SRS unit connector A (28P).
50. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the SRS unit.
NO -
- With TPMS: Go to step 51.
- Without TPMS: 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.
51. Turn the ignition switch OFF.
52. Reconnect SRS unit connector A (28P).
53. Disconnect the TPMS control unit 20P connector.
54. Turn the ignition switch ON (II), and read the HDS.
Does the HDS identify the vehicle?
YES - Replace the TPMS control 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.