Audio/Video

U0020-CAN B BUS OFF PERFORMANCE

U0020 - Can B Bus Off Performance:

WHEN MONITORED
Continuously.

SET MONITORED
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 CONDITION




Turn 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.

Q: 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. Body Verification Test

2. CHECK FRONT CONTROL MODULE DTCs




With the scan tool, read Front Control Module DTCs

Q: 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.
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.

Q: Is the resistance below 2.0 ohms?

YES: Go To 4. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the Can B Bus (+) circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

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.

Q: Is the resistance below 2.0 ohms?

YES: Replace the Amplifier. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the Can B Bus (-) circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test