Inspection Procedure 4

The "SECURITY" Indicator Light does not Illuminate.

The Security Indicator Circuit Part 1:

The Security Indicator Circuit Part 2:

CIRCUIT OPERATION
If the requirements for starting the engine are not satisfied, the immobilizer-ECU flashes the "SECURITY" indicator for 30 seconds.

TECHNICAL DESCRIPTION (COMMENT)
There may be burned out bulb of the "SECURITY" indicator light or a malfunction of the combination meter (printed-circuit board) or immobilizer-ECU.

NOTE: The "SECURITY" indicator light is shared by the "SECURITY" system. If a problem can not be resolved, observe the "SECURITY" system troubleshooting (Refer to Theft Alarm System Diagnosis). Theft-Alarm System

TROUBLESHOOTING HINTS
- Burned out bulb of "SECURITY" indicator light
- Malfunction of combination meter (printed-circuit board)
- Malfunction of immobilizer-ECU
- Damaged wiring harness or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991911: Main Harness B (Vehicles without CAN communication system)

STEP 1. Check the "SECURITY" indicator light circuit of immobilizer-ECU connector C-79.

1. Disconnect the immobilizer-ECU connector C-79 and measure at the harness side.




2. Connect terminal 9 to the ground.
3. Ignition switch "ON" position.

Q: Is the only "SECURITY" indicator light illuminate? (other indicator lights are good condition)

YES: Replace the immobilizer-ECU. Then register the password (secret code) and encrypted code (Refer to How To Register Encrypted Code).

NO: Go to Step 2.

STEP 2. Check the "SECURITY" indicator light




1. Remove the combination meter and remove the "SECURITY" indicator light bulb.
2. Check the bulb.

Q: Is the "SECURITY" indicator light damaged?

YES: Replace it.

NO: Go to Step 3.







STEP 3. Check the immobilizer-ECU connector C-79 and combination meter connector C-42 for damage.

Q: Are the immobilizer-ECU connector C-79 and combination meter connector C-42 damaged?

YES: Repair or replace the connector. Refer to Harness Connector Inspection. Confirm that scan tool MB991502 communicates normally.

NO: Go to Step 4.







STEP 4. Check the wiring harness between immobilizer-ECU connector C-79 (terminal 9) and combination meter connector C-42 (terminal 31).

Q: Are immobilizer-ECU connector C-79 (terminal 9) and combination meter connector C-42 (terminal 31) damaged?

YES: Repair the wiring harness. Refer to Harness Connector Inspection.

NO: Repair the combination meter (printed-circuit board) (Refer to Combination Meter Assembly And Vehicle Speed Sensor - Disassembly And Assembly). Then Go to Step 5.

STEP 5. Recheck for malfunction.

Q: Is a malfunction eliminated?

YES: 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 Point.)

NO: Go to step 1.