Diagnostic Test
- 1) TEST FOR INTERMITTENT CONDITION
Turn the ignition on.
Cycle the ignition from on to off 3 times.
With the scan tool, record and erase DTCs.
Turn the ignition on
With the scan tool, read DTCs.
Does the scan tool display: U0020-CAN B BUS OFF PERFORMANCE?
Yes
- Go to Step 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 the BODY VERIFICATION TEST - VER 1 .
- 2) CHECK FRONT CONTROL MODULE DTCs
With the scan tool, read Totally Integrated Power Module DTCs.
Does the scan tool display any CAN B BUS DTCs - ACTIVE?
Yes
- Refer to the symptom list for problems related to Communication. Refer to DIAGNOSIS AND TESTING .
No
- Go to Step 3.
- 3) CAN B BUS (+) CIRCUIT OPEN
Turn the ignition off.
Disconnect the Amplifier C1 harness connector.
Disconnect the Totally Integrated Power Module C3 harness connector.
Measure the resistance of the (D55) CAN B BUS (+) circuit between the Totally Integrated Power module C3 harness connector and the Amplifier C1 harness connector.
Is the resistance below 2.0 ohms?
Yes
- Go to Step 4.
- Perform the BODY VERIFICATION TEST - VER 1 .
No
- Repair the CAN B BUS (+) circuit for an open.
- Perform the BODY VERIFICATION TEST - VER 1 .
- 4) CAN B BUS (-) CIRCUIT OPEN
Measure the resistance of the (D54) CAN B BUS (-) circuit between the Totally Integrated Power Module C3 harness connector and the Amplifier C1 harness connector.
Is the resistance below 2.0 ohms?
Yes
- Replace the Amplifier in accordance with the service information.
- Perform the BODY VERIFICATION TEST - VER 1 .
No
- Repair the CAN B BUS (-) circuit for an open.
- Perform the BODY VERIFICATION TEST - VER 1 .