Inspection Procedure 26: 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/short circuit or harness damage in engine oil pressure switch circuit or loose connector contact
  • Lack of oil pressure
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-28 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-28 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. Connector check: B-30-4 oil pressure switch connector

Q. Is the check result normal?
Go to Step 4 .
Repair the connector.

STEP 4. Check harness between B-30-4 (terminal No. 1) engine oil pressure switch connector and B-28 (terminal No. 140) engine-ECU connector.
note Before checking harness, check intermediate connectors A-11 and B-30, and repair if necessary.

  • Check output line for open/short circuit and damage.

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 <BWC> ).

Q. Is the check result normal?
Go to Step 6 .
Repair the oil pressure.

STEP 6. Replace the engine oil pressure switch.

  • After replacing the engine oil pressure switch, re-check the trouble symptoms.

Q. Does trouble symptom persist?
Replace the engine-ECU.
The check is end.