Inspection Procedure 27: Engine Oil Pressure Switch System

OPERATION

The battery voltage is applied to the engine oil pressure switch (terminal No. 1) from the engine-ECU (terminal No. 140).

FUNCTION

When the oil pressure switch is in ON position, the signal meaning the engine oil pressure switch is input into the engine-ECU. The engine-ECU controls the oil pressure warning lamp based on this signal.

PROBABLE CAUSES

Failed engine oil pressure switch
Open or shorted engine oil pressure switch circuit, harness damage, or connector damage
Lack of oil pressure
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-06 engine-ECU connector

Q. Is the check result normal?

	Go to Step 2 .

	Repair or replace the connector.

STEP 2. Perform voltage measurement at B-06 engine-ECU connector.

Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992044) to measure at connector for inspection.
Voltage between terminal No. 140 and earth.

OK:
0 - 1 V (Idling after warming up)
System voltage (Ignition switch: ON)

Q. Is the check result normal?

	Check combination meter (Refer to GROUP 54A - Combination Meter - Check Chart for Trouble Symptoms ).

	Go to Step 3 .

STEP 3. Check harness between B-02-4 (terminal No. 1) oil pressure switch connector and B-06 (terminal No. 140) engine-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 4 .

	Repair.

STEP 4. Connector check: B-02-4 oil pressure switch connector

Q. Is the check result normal?

	Go to Step 5 .

	Repair.

STEP 5. Oil pressure check

Oil pressure check (Refer to GROUP 12 - On-vehicle Service - Oil Pressure Check ).

Q. Is the check result normal?

	Go to Step 6 .

	Repair the oil pressure.

STEP 6. Check the engine oil pressure switch

Check the engine oil pressure switch (Refer to GROUP 12 - On-vehicle Service - Engine Oil Pressure Switch ).

Q. Is the check result normal?

	Go to Step 7 .

	Replace the engine oil pressure switch.

STEP 7. Check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).