Inspection Procedure 3

Inspection procedure 3:The SRS Warning Light Does Not Illuminate.

SRS Warning Light Circuit (Part 1):

SRS Warning Light Circuit (Part 2):

CIRCUIT OPERATION
- The SRS warning light illuminates when the ignition switch is turned to the "ON" position and goes out after approximately seven seconds if there is not a malfunction in the SRS system.
- SRS-ECU sends the SRS warning light signal to the combination meter via the CAN communication.
- As a cause, the failure of CAN bus line, combination meter, or SRS-ECU is suspected.

TROUBLESHOOTING HINTS
- Damaged wiring harness and connectors
- Combination meter malfunction
- Malfunction of 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. Using scan tool MB991958, diagnose the CAN bus line.







CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

Use scan tool MB991958 to diagnose the CAN bus lines.

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.

Q: Is the check result satisfactory?

YES: Go to Step 2.

NO: Repair the CAN bus line.

STEP 2. Using scan tool MB991958, check actuator test

Check the SRS-ECU actuator tests.Item No. 01: SRS warning light

Q: Does the SRS warning light turn on and off normally?

YES: Go to Step 3.

NO: Replace SRS-ECU.

STEP 3. Using scan tool MB991958, check actuator test

Check the combination meter actuator tests.
Item No. 07: Indicator 1

Q: Does the SRS warning light turn on and off normally?

YES: Go to Step 4.

NO: Replace the combination meter.

STEP 4. Wiring harness inspection between C-317ETACS-ECU connector terminal No. 5 and C-04combination meter connector terminal No. 2

NOTE: Prior to the wiring harness inspection, check the ETACS-ECU connector C-317 and combination meter connector C-04, and repair if necessary.

- The SRS warning light inspection for open and short circuit

Q: Is the check result normal?

YES: If other systems which receive IG1 signal are normally operated, replace the combination meter.

NO: Repair the wiring harness.