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.

TROUBLE JUDGMENT
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 diagnosis code is reset.
Check again if the diagnosis code is set to the CAN box unit.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check if diagnosis code is set.

Q. Is the diagnosis code set?
Replace the CAN box unit.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).