Inspection Procedure 3

Service Engine Soon/Malfunction Indicator Lamp Circuit:

Connector: C-89:

CIRCUIT OPERATION
- The service engine soon/malfunction indicator lamp power is supplied from the ignition switch.
- The PCM controls the ground of the service engine soon/malfunction indicator lamp by turning the power transistor in the PCM "ON" and "OFF".

COMMENT
- The PCM causes the service engine soon/malfunction indicator lamp to illuminate for 5 seconds immediately after the ignition switch is turned to "ON" occurred.

TROUBLESHOOTING HINTS
The most likely causes for this case:
- Burnt-out bulb.
- Defective service engine soon/malfunction indicator lamp circuit.
- Malfunction of the PCM.

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

CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.




STEP 1. Using scan tool MB991502, check data list item 16: Power Supply Voltage.
- Voltage should be approximately 12 volts (battery positive voltage).

If within specifications, go to Step 2.

If not within specifications, refer to INSPECTION PROCEDURE 28 - Power Supply System and Ignition Switch - IG System.




STEP 2. Check the circuit at the PCM connector C-89.
1. Disconnect connector C-89 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Using a jumper wire, ground terminal 22 to the ground.

- The check engine/malfunction indicator lamp should illuminate.

4. Turn the ignition switch "OFF".
If the lamp does not illuminate, go to Step 3. If the lamp illuminates, go to Step 6.

STEP 3. Check the burnt-out bulb.
If not burnt out, go to Step 4.

If burnt out, replace the bulb. Then confirm that the malfunction symptom is eliminated.




STEP 4. Check the circuit at the combination meter connector C-04.
1. Disconnect connector C-04 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Connect terminal 24 and the ground via a 20-ohms resistor.

Measure the current at this time.
- The current should be 0.5 ampere or more.

4. Turn the ignition switch "OFF".
If within specifications, go to Step 5.

If not within specifications, check the harness wire and connector between the combination meter and the ignition switch, and repair or replace. Refer to vehicle level Testing and Inspection. Then confirm that the malfunction symptom is eliminated.







STEP 5. Check the harness wire between the combination meter connector C-04 and the PCM connector C-89.

NOTE: After inspecting the intermediate connector C-16, inspect the wire. If the intermediate connector C-16 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection. Then confirm that the malfunction symptom is eliminated.

If the wire between the combination meter connector C-04 and the PCM connector C-89 is damaged, repair it.

If the wire between the combination meter connector C-04 and the PCM connector C-89 is damaged, repair or replace the combination meter connector C-04. Refer to vehicle level Testing and Inspection.

Then confirm that the malfunction symptom is eliminated.




STEP 6. Check harness connector C-89 at the PCM for damage.
If harness connector C-89 is damaged, repair or replace it.
Refer to Harness Connector Inspection at vehicle level Testing And Inspection.

If harness connector C-89 is in good condition, replace the PCM.

Then confirm that the malfunction symptom is eliminated.