Code No.03 Communication Error with Front-ECU


caution If diagnosis code No.03 is set in the ETACS-ECU, diagnose the CAN bus lines.
note When the diagnosis codes relating to the CAN communication error are set, make sure of the vehicle equipment. When the vehicle is not equipped with the system the SWS communicates to, the diagnosis code is always set. This is not abnormal.

TROUBLE JUDGMENT
The ETACS-ECU communicates with the front-ECU through the SWS communication line. If there is any trouble in that communication, diagnosis code No.03 will be set.

COMMENTS ON TROUBLE SYMPTOM
The front-ECU, the ETACS-ECU, connector(s), or wiring harness between the two may be defective.

PROBABLE CAUSES

  • Malfunction of the front-ECU
  • Malfunction of the ETACS-ECU
  • Damaged harness wires and connectors

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 54D - Troubleshooting ).

STEP 2. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Ignition switch: LOCK (OFF) position to ON
(3)On completion, check that the diagnosis code is not reset.

Q. Is the diagnosis code set?
Go to Step 3.
If a trouble is solved, it is determined that there is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ).

STEP 3. ECU check by using the SWS monitor
Check that the power supply and earth lines to the ETACS-ECU and the front-ECU and the SWS communication lines are normal.

  • Ignition switch: OFF
ECUS TO BE CHECKED
  • Front ECU
  • ETACS ECU
OK: "OK" are displayed for all the items

Q. Are the check result normal?
YES <Normal conditions are displayed for all the items.> : Intermittent malfunction (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ).
NO <"NG" is displayed on the "ETACS ECU" menu.> : Refer to Inspection Procedure 2 "Communication with the ETACS-ECU is not possible ."
NO <"NG" is displayed on the "FRONT ECU" menu.> : Refer to Inspection Procedure 3 "Communication with the front-ECU is not possible ."