Light Does Not Illuminate

SRS Warning Light Drive Circuit System Fault 1 (Light does not Illuminate.)

SRS Warning Light Drive Circuit:

Connectors:

CIRCUIT OPERATION
- Power for the SRS warning light is supplied from the ignition switch (IG1).
- 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.

DTC SET CONDITIONS
This DTC is set when an open circuit is detected for a continuous period of five seconds while the SRS-ECU is monitoring the SRS warning light and the light is OFF. (transistor OFF) However, if the vehicle condition returns to normal, the DTC 43 will be automatically erased, and the SRS warning light will go out.

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU
- Malfunction of the combination meter

DIAGNOSIS

Required Special Tools:
- MB991502: Scan Tool(MUT-II)
- MB991223 (MB991222): Harness Set (Probe)

STEP 1. Check the SRS warning light.
1. Connect the negative battery terminal.




2. Disconnected the SRS-ECU connector C-137.
3. Turn the ignition switch to the "ON" position.

Q: Does the warning light illuminate?

YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 43 sets, replace the SRS-ECU. Then go to Step 5.
NO: Go to Step 2.

STEP 2. Check the ground line at the SRS-ECU connector C-137.




1. Disconnect the SRS-ECU connector C-137.

CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.




2. Measure the continuity between the C-137 harness side connector terminal 3 and ground.
It should be less than 2 ohms.

Q: Is the continuity normal?

YES: Go to Step 3.
NO: Go to Step 4.







STEP 3. Check the harness wires for open circuit between the ignition switch connector C-202 (terminal No.2) and the combination meter C-101 (terminal No.12), and between the combination meter C-101 (terminal No.8) and the SRS-ECU connector C-137 (terminal No.4).

NOTE: After inspecting the intermediate connectors C-101, C-308 and C-311, inspect the wiring harness. If the intermediate connector C-101, C-308, or C-311 is damaged, repair or replace it. Refer to Harness Connector Inspection. Then go to Step 5.







Q: Are the harness wires between the SRS-ECU connector C-137 (terminal No.4) and the ignition switch connector C-202 (terminal No.2) in good condition?

YES: Replace the combination meter. (Refer to Combination Meters Assembly and Vehicle Speed Sensor.) Then go to Step 5.
NO: Repair the harness wires between the SRS-ECU connector C-137 and the ignition switch connector C-202. Then go to Step 5.







STEP 4. Check the harness wire for open circuit between the SRS-ECU connector C-137 (terminal No.3) and ground.

Q: Is the harness wire between the SRS-ECU connector C-137 (terminal No.3) and ground in good condition?

YES: Go to Step 5.
NO: Repair the harness wire between the SRS-ECU connector C-137 and ground. Then go to Step 5.

STEP 5. Check for DTC.

Q: Is DTC 43 set?

YES: Return to Step 1.
NO: The procedure is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. Refer to INTRODUCTION, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)