Inspection Procedure 3
Service Engine Soon/Malfunction Indicator Lamp Circuit:
Connector: C-51 <M/T>, C-52 <A/T>:
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" position 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 the PCM.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 1. Using scan tool MB991502, check data list item 16: Power Supply Voltage.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Set scan tool MB991502 to the data reading mode for item 16, Power Supply Voltage.
- Voltage should be 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 for a burnt-out bulb.
If not burnt out, go to Step 3.
If burnt out, replace the bulb.
Then confirm that the malfunction symptom is eliminated.
STEP 3. Check the circuit at combination meter connector C-41.
1. Disconnect connector C-41 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 52 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to "LOCK" (OFF) position.
If within specifications, go to Step 4.
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 4. Check harness connector C-1 at the combination meter connector for damage.
If harness connector C-41 is good condition, go to Step 5.
If harness connector C-41 is damaged, repair or replace it.
Refer to Harness Connector Inspection.
Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the circuit at ECM connector C-51
1. Disconnect connector C-51
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 22 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to "LOCK" (OFF) position.
If within specifications, go to Step 6.
If not within specifications, check intermediate connector C-28, and repair or replace as required.
Refer to Harness Connector Inspection.
If intermediate connector C-28 is in good condition, repair the harness wire between combination meter connector C-41 and ECM connector C-51
Then confirm that the malfunction symptom is eliminated.
STEP 6. Check harness connector C-51 at the ECM
If harness connector C-51
If harness connector C-51
Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.