Restraints
U0020-CAN B BUS OFF PERFORMANCE
For a complete wiring diagram Refer to Diagrams/Electrical.
- When Monitored:
Continuously
- Set Condition:
Whenever the CAN B Bus (+) or CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.
Diagnostic Test
1.VERIFY DTC U0020-CAN B BUS OFF PERFORMANCE IS ACTIVE
Turn 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
- If the DTC is stored, check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
- Perform *ORC VERIFICATION TEST - VER 1. Occupant Restraint Controller (ORC) Verification Test
2.CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE FRONT CONTROL MODULE (FCM)
With the scan tool, read Front Control Module (FCM) DTCs
Does the scan tool display any active CAN B BUS related DTCs?
Yes
- Diagnose and repair the DTC(s).
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 C1 connector.
Disconnect the Front Control Module (FCM) C1 connector.
Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module C1 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 *OCS VERIFICATION TEST - VER 1. Verification Tests
4.CHECK (D54) CAN B BUS (-) CIRCUIT FOR AN OPEN
Measure the resistance of the (D54) CAN B Bus (-) circuit between the Front Control Module C1 connector and the OCM C1 connector.
Is the resistance below 2.0 ohms?
Yes
- Replace the OCM.
- Perform *OCS VERIFICATION TEST - VER 1. Verification Tests
No
- Repair the (D54) CAN B Bus (-) circuit for an open.
- Perform *OCS VERIFICATION TEST - VER 1. Verification Tests