SRS-ECU

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

JUDGEMENT CRITERIA
Because of the CAN-B bus circuit malfunction, if SRS-ECU becomes unable to perform the normal data transmission, SRS-ECU determines that an 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". Scan Tool Connecting
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 : Repair the CAN bus line (Refer to Controller area network Diagnosis).

STEP 2. Recheck for diagnostic trouble code.

Check again if the DTC is set to the SRS-ECU.

1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES : Replace the SRS-ECU.

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