Inspection Procedure 1

Inspection Procedure 1: Scan tool cannot communicate only with ABS-ECU.

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines CAN Bus Diagnostics Chart).

- Whenever ECU is replaced, ensure that the CAN bus lines are normal.

- If the power is supplied with the ground circuit of CAN communication device open circuited, an electric potential abnormality may occur to the CAN bus lines.

COMMENTS ON TROUBLE SYMPTOM

When scan tool cannot communicate with the ABS system, the CAN bus line, ABS-ECU power supply circuit system, or ABS-ECU may be faulty.

PROBABLE CAUSES

- Damaged wiring harness and connectors

- ABS-ECU malfunction

- Wrong routing of M.U.T.-III harness

- Abnormality in battery or generator

- Abnormality in power supply voltage to ABS-ECU

- ECU malfunction of other system

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. Using scan tool MB991958, diagnose the CAN bus line.

Use scan tool to diagnose the CAN bus lines.

Q. Is the check result normal?

YES Check the power supply circuit, and repair if necessary (Refer to Inspection Procedure 8).
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).