Code No.U0019 Bus off (CAN-B)


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
  • Before replacing the CAN box unit, be sure to check that the power supply circuit, earth circuit, and communication circuit are normal. (Check that the voltage is 10 V or more.)

TROUBLE JUDGEMENT
When the CAN box unit is returned from the bus off state, or when the bus error is indicated to the CAN box unit state, the diagnosis code U0019 (CAN-B) is set.

COMMENTS ON TROUBLE SYMPTOM
The CAN box unit, power supply for the CAN box unit, earth circuit, or CAN bus line may have a problem.

PROBABLE CAUSES

  • Malfunctions of CAN box unit
  • Malfunction of CAN bus line wiring harness and connector

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).

STEP 2. Check whether the M.U.T.-III can communicate with the CAN box unit.

Q. Is the check result normal?
Erase the diagnosis code. This diagnosis is complete.
Check the power supply circuit of the CAN box unit, and repair if necessary.