Inspection Procedure 3

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

COMMENT
- The ECM or 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 ECM .
- Malfunction of PCM .

WIRING DIAGRAM

CONNECTORS

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 29 - Power Supply and Ignition Switch - IG System.

STEP 2. Check the circuit at the ECM connector C-36 or PCM connector C-39 .
1. Disconnect connector C-36 or C-39 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Using a jumper wire, ground terminal 36 or 22 to the ground.
- The service engine soon/malfunction indicator lamp should illuminate.
4. Turn the ignition switch "OFF."
If the lamp does not illuminate, go to Step 3. If the lamp illuminate, 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-29.
1. Disconnect connector C-29 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect terminal 29 and the ground via a 20-Ohm 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 Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.

STEP 5. Check the harness wire between the combination meter connector C-30 and the ECM connector C-36 or PCM connector C-39 .

NOTE: After inspecting the intermediate connector C-17, Inspect the wire. If the intermediate connector C-17 is damaged, repair or replace it. Refer to Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.

If the wire between the combination meter connector C-30 and the ECM connector C-36 or PCM connector C-39 is damaged, repair it.
If the wire between the combination meter connector C-30 and the ECM connector C-36 or PCM connector C-39 is damaged, repair or replace the combination meter connector C-30. Refer to Harness Connector Inspection >.
Then confirm that the malfunction symptom is eliminated.

STEP 6. Check harness connector C-36 at the ECM or harness connector C-39 at the PCM for damage.
If harness connector C-36 or C-39 is damaged, repair or replace it. Refer to Harness Connector Inspection >.
If harness connector C-36 or C-39 is normal, replace the ECM or PCM.
Then confirm that the malfunction symptom is eliminated.