U0020-CAN B BUS OFF PERFORMANCE
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
- Continuously.
- Set Condition:
- Whenever the Can B Bus (+) or B Bus (–) circuit is open, shorted to voltage or shorted to ground, this code will set.
| Possible Causes |
| CAN B BUS DTCs IN FRONT CONTROL MODULE |
| (D54) CAN B BUS (–) CIRCUIT OPEN |
| (D55) CAN B BUS (+) CIRCUIT OPEN |
| AMPLIFIER |
Diagnostic Test
1. TEST FOR INTERMITTENT CONDITIONTurn the ignition on.
With the scan tool, record and erase DTCs
Cycle the ignition from on to off 3 times.
Turn the ignition on.
With the scan tool, read DTCs.
Does the scan tool display U0020-CAN B BUS OFF PERFORMANCE?
Yes
- Go To 2
No
- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
- Perform BODY VERIFICATION TEST - VER 1.
2. CHECK FRONT CONTROL MODULE DTCs
With the scan tool, read Front Control Module DTCs
Does the scan tool display any CAN B BUS DTCs – ACTIVE?
Yes
- Refer to the symptom list for problems related to Communication in the ELECTRICAL.– ELECTRONIC CONTROL MODULES – ELECTRICAL DIAGNOSES section.
No
- Go to 3
3. CAN B BUS (+) CIRCUIT OPEN
Turn the ignition off.
Disconnect the Amplifier harness connector.
Disconnect the Front Control Module C1 harness connector.
Measure the resistance of the (D55) Can B Bus (+) circuit between the Front Control Module C1 harness connector and the Amplifier harness connector.
Is the resistance below 2.0 ohms?
Yes
- Go To 4
- Perform BODY VERIFICATION TEST - VER 1.
No
- Repair the Can B Bus (+) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1.
4. CAN B BUS (–) CIRCUIT OPEN
Measure the resistance of the (D54) Can B Bus (–) circuit between the Front Control Module C1 harness connector and the Amplifier harness connector.
Is the resistance below 2.0 ohms?
Yes
- Replace the Amplifier in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1.
No
- Repair the Can B Bus (–) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1.