Inspection Procedure 1

INSPECTION PROCEDURE 1: Communication between the Scan Tool and the SRS-ECU is not possible.

Diagnosis Connector Circuit:

TECHNICAL DESCRIPTION (COMMENT)
If the scan tool (M.U.T.-III Sub Assembly) can not communicate with the SRS system, the CAN bus lines may be defective. If the SRS system does not work, the SRS-ECU or its power supply circuit may be defective.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Damaged wiring harness or connector
- Malfunction of the SRS-ECU

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 (Vehicles with CAN communication system)

STEP 1. V.C.I. status check

Check that the V.C.I. indicator light is illuminated in green.

Q: Is it illuminated in green?

YES: Diagnose the CAN bus line, and repair if necessary. (Refer to Information Bus, Diagnosis)

NO: Go to Step 2.

STEP 2. Connector check: C-317 ETACS-ECU connector, C-125 data link connector

Q: Is the check result normal?

YES: Go to Step 3.

NO: Repair the connector concerned.

STEP 3. Wiring harness check between the C-317 ETACS-ECU connector No. 8 and the C-125 data link connector terminal No. 16

Check the power supply line for open circuit.

Q: Is the check result normal?

YES: Go to Step 4.

NO: Repair the wiring harness.

STEP 4. Wiring harness check between the C-125 data link connector terminal No. 4 or 5 and the ground

Check the ground wires for open circuit.

Q: Is the check result normal?

YES: Check the scan tool.

NO: Repair the wiring harness.