Audio/Video

U0020-CAN B BUS OFF PERFORMANCE




WHEN MONITORED
Continuously.

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