Body Control Systems

U0021-CAN B BUS (+) CIRCUIT OPEN





For complete wiring diagram refer to the wiring section.

WHEN MONITORED
Continuously.

SET CONDITION
The FCM detects the (D55) CAN B Bus (+) circuit is open.

POSSIBLE CAUSES
- (D55) Can B bus (+) circuit open
- Front control module

DIAGNOSTIC TEST

1. TEST FOR INTERMITTENT CONDITION
Turn the ignition on.
With the scan tool, record and erase FCM DTC's
Cycle the ignition from on to off 3 times.
Turn the ignition on.
With the scan tool, read active FCM DTC's.

Q: Does the scan tool display this DTC as active?

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.




2. (D55) CAN B BUS (+) CIRCUIT OPEN
Turn the ignition off.
Disconnect the Front Control Module C1 harness connector.
Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.

Q: Is there any voltage present?

YES: Inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Front Control Module in accordance with the service information. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the (D55) CAN B Bus (+) circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test