SRS

DTC U0019: Bus Off (CAN-B)

CAUTION: If the DTC U0019 is set, be sure to diagnose the CAN main bus line.When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSTIC FUNCTION
If the CAN-B circuit malfunction occurs, the SRS-ECU sets the DTC U0019.

JUDGMENT CRITERIA
Because of the CAN-B bus circuit malfunction, if SRS-ECU becomes unable to perform the normal data transmission, SRS-ECU determines that abnormality is present.

TROUBLESHOOTING HINTS
The CAN bus line may be defective

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicles Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)




STEP 1. Using scan tool MB991958, diagnose the CAN bus line

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958. Refer to "How to connect the scan tool."
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES: Go to Step 2.

NO: The trouble can be an intermittent malfunction (Refer to - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

STEP 2. Using scan tool MB991958, diagnose the CAN bus line.

1. Turn the ignition switch to the "ON" position.
2. Diagnose the CAN bus line.
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES: There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to How to use Troubleshooting/inspection Service Points).

NO: Repair the CAN bus line. (Refer to Information Bus, Diagnosis).