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 CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.
| Possible Causes |
| ACTIVE U0020-CAN B BUS DTC IN OCCUPANT CLASSIFICATION MODULE (OCM) |
| (D55) CAN B BUS (+) CIRCUIT OPEN |
| (D54) CAN B BUS (-) CIRCUIT OPEN |
| OCCUPANT CLASSIFICATION MODULE (OCM) |
Diagnostic Test
1. VERIFY DTC U0020-CAN B BUS OFF PERFORMANCE IS ACTIVETurn the ignition on.
With the scan tool, read Occupant Classification Module (OCM) DTCs.
Does the scan tool display active: U0020-CAN B BUS OFF PERFORMANCE?
Yes
- Go To 2
No
- Perform *STORED LOST COMMUNICATION DTCS diagnostic test. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
2. CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE TOTALLY INTEGRATED POWER MODULE (TIPM)
With the scan tool, read TIPM DTCs
Does the scan tool display any active CAN B BUS related DTCs?
Yes
- Diagnose and repair the DTC(s). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING) .
No
- Go To 3
3. CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN
Turn the ignition off.
Disconnect the negative battery cable.
Disconnect the OCM connectors.
Disconnect the TIPM C7 connector.
Measure the resistance of the (D55) CAN B Bus (+) circuit between the TIPM C7 connector and the OCM C1 connector.
Is the resistance below 2.0 ohms?
Yes
- Go To 4
No
- Repair the (D55) CAN B Bus (+) circuit for an open.
- Perform *OCM SYSTEM VERIFICATION TEST.
4. CHECK (D54) CAN B BUS (–) CIRCUIT FOR AN OPEN
Measure the resistance of the (D54) CAN B Bus (–) circuit between the TIPM C7 connector and the OCM C1 connector.
Is the resistance below 2.0 ohms?
Yes
- Go To 5
No
- Repair the (D54) CAN B Bus (–) circuit for an open.
- Perform *OCM SYSTEM VERIFICATION TEST.
5. REPLACE THE OCCUPANT CLASSIFICATION MODULE
WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.
Repair
- Replace the OCM in accordance with the Service Information.
- Perform *OCM SYSTEM VERIFICATION TEST.