Wireless Control Module (WCM)

DTC U0019: Bus off (CAN-B)

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

DTC SET CONDITION
If the CAN-B circuit malfunctions, the WCM sets DTC U0019.

TECHNICAL DESCRIPTION(COMMENT)
If WCM cannot perform the data transmission in normal conditions due to a malfunction of the CAN-B bus circuit, WCM determines that there is a problem.

TROUBLESHOOTING HINT
The CAN bus line may be defective

DIAGNOSIS

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

STEP 1.Recheck for diagnostic trouble code.

Check again if the DTC is set to the WCM.






CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan toolMB991958.

1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool(M.U.T.-III)." Scan Tool Connecting
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: Go to Step 2.

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).

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: 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).

NO: Repair the CAN bus line (Refer to Controller Area Network, Diagnosis).