Restraints

U0020-CAN B BUS OFF PERFORMANCE





For a complete wiring diagram Consult 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 IS ACTIVE
Turn the ignition on.
With the scan tool, read Occupant Classification Module (OCM) DTCs.
Does the scan tool display active: U0019-CAN B BUS?

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 *AIRBAG SYSTEM VERIFICATION TEST - VER 1.Airbag System 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).Testing and Inspection.

No

- Go To 3

3. CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN




Turn the ignition off.
Disconnect the negative battery cable.

WARNING: To avoid serious or fatal injury, turn the ignition off, disconnect the battery and wait two minutes before proceeding.
Disconnect the OCM connectors.
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 *OCCUPANT CLASSIFICATION MODULE SYSTEM VERIFICATION TEST.Occupant Classification Module (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 Front Control Module C1 connector and the OCM C1 connector.
Is the resistance below 2.0 ohms?

Yes

- Replace the OCM.
- Perform *OCCUPANT CLASSIFICATION MODULE SYSTEM VERIFICATION TEST.Occupant Classification Module (OCM) System Verification Test

No

- Repair the (D54) CAN B Bus (-) circuit for an open.
- Perform *OCCUPANT CLASSIFICATION MODULE SYSTEM VERIFICATION TEST.Occupant Classification Module (OCM) System Verification Test