SRS Warning Light Drive Circuit System Fault 1 (Light Does Not Switch Off)

SRS Warning Light Drive Circuit System Fault 1 (Light Does Not Switch Off.)

SRS Warning Light Drive Circuit Part 1:

SRS Warning Light Drive Circuit Part 2:

CIRCUIT OPERATION
- Power for the SRS warning light is supplied from the ignition switch (IG1) circuit.
- The SRS warning light illuminates when the ignition switch is turned "ON" 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 a short to ground occurs in the harness between the SRS warning light and SRS-ECU while SRS-ECU is monitoring the light and the light is ON. However, if the vehicle condition returns to normal, DTC 43 will be automatically erased, and the SRS warning light will go out.

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

Required Special Tool:
- MB991502: Scan Tool (MUT-II)

STEP 1. Check SRS-ECU connector C-72 for damage.







1. Disconnect SRS-ECU connectors C-72.
2. Check the short bar for the warning light inside the harness side connector for improper contact or deformation.

Q: Is SRS-ECU connectors C-72 good condition?

YES: Then go to Step 2.

NO: Repair or replace the SRS-ECU connector C-72. Then go to Step 4.

STEP 2. Check the SRS warning light.

1. Disconnect the combination meter connector C-42.
2. Connect the negative battery cable.
3. Turn the ignition switch to the "ON" position.







Q: Does the SRS warning light go out when combination meter connector C-42 is disconnected?

YES: Go to Step 3.

NO: Replace the combination meter. Then go to Step 4.







STEP 3. Check the harness for short circuit to ground between SRS-ECU connector C-72 (terminal No.3) and combination meter connector C-42 (terminal No.25).

Q: Is the harness wire between the SRS-ECU connector C-72 (terminal No.3) and combination meter connector C-42 (terminal No.25) in good condition?

YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 43 sets, replace the SRS-ECU. Then go to Step 4.

NO: Repair the harness wire between SRS-ECU connector C-72 and combination meter connector C-42. Then go to Step 4.

STEP 4. Check for DTC.

Q: Is DTC 43 output?

YES: There is no action to be taken.

NO: This diagnosis is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)