Inspection Procedure 4

Inspection Procedure 4: The SRS warning light does not go out.

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 CAN Bus Diagnostics Chart).

STEP 2. Recheck of the SRS warning light

(1)Connect the negative battery terminal.

(2)Ignition switch: ON

Q. Does the SRS warning light illuminate for approximately 7 seconds and then go out after the ignition switch is turned to the "ON" position?

YES There is an intermittent malfunction such as poor engaged connector(s) or open circuit How to Cope With Intermittent Malfunctions).
NO Go to Step 3.
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. Removal and Replacement.)
STEP 4. Recheck for diagnostic trouble code.

Check again if the DTC is set.

(1)Erase the DTC.

(2)Turn the ignition switch to the "ON" position.

(3)Check if the DTC is set.

(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC set?

YES Troubleshoot for the relevant DTC.
NO Go to Step 5
STEP 5. Recheck of the SRS warning light

(1)Connect the negative battery terminal.

(2)Ignition switch: ON

Q. Does the light stay on?

YES Replace the SRS-ECU (Refer to Service and Repair).
NO The procedure is complete.