Inspection Procedure 26

Inspection Procedure 26: Engine Oil Pressure Switch (For Warning Lamp) System

Engine Oil Pressure Switch (For Warning Lamp) Circuit:

CIRCUIT OPERATION
- Battery voltage is applied to the oil pressure switch (terminal No. 1) from the engine-ECU (terminal No. 36).

COMMENT
- Detect the engine oil pressure conditions and enter the result into the ECM. After starting the engine if the oil pressure rises to higher than the given pressure, the engine oil pressure switch turns OFF. Under this condition the ECM sends the command of turning off the oil warning lamp to the combination meter via CAN.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Engine oil pressure switch failed.
- Improper connector contact, open circuit or short-circuit harness wire.
- ECM failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Check harness connector B-16 at engine oil pressure switch and harness connector B-10 at ECM for damage.

Q: Is the harness connector in good condition?

YES : Go to Step 2.

NO : Repair or replace it. Refer to General (Electrical), Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

STEP 2. Measure the power supply voltage at engine oil pressure switch connector B-16.

1. Disconnect the connector B-16 measure at the harness side.
2. Turn the ignition switch to the "ON" position.

3. Measure the voltage between terminal No. 1 and ground.
- The voltage should equal battery positive voltage.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES : Go to Step 5.

NO : Go to Step 3.

STEP 3. Check for open circuit or short circuit to ground or harness damage between engine oil pressure switch connector B-16 and ECM connector B-10.

1. Disconnect the connector B-16 and B-10 measure at the harness side.

2. Measure the resistance between connector B-16 (terminal No. 1) and connector B-10 (terminal No. 36).
- Should be less than 2 ohms.

3. Check for the continuity between connector B-10 (terminal No. 36) and ground.
- Not continuity.

Q: Is the harness wire in good condition?

YES : Then go to Step 4.

NO : Repair it. Then confirm that the malfunction symptom is eliminated.

STEP 4. Measure the voltage at ECM connector B-10 by using power plant ECU check harness special tool MB992110.

1. Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.

2. Measure the voltage between terminal No. 36 and ground.

OK : 1 V or less (ignition switch: ON)

System voltage (during idling)

Q :

YES : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points-How to Cope with Intermittent Malfunctions.

NO : Replace the ECM. When the ECM is replaced, register the ID code. Refer to Diagnosis-ID Codes Registration Judgment Table [Vehicles with KOS] or Diagnosis-ID Codes Registration Judgment Table [Vehicles with WCM].

STEP 5. Measure the voltage at ECM connector B-10 by using power plant ECU check harness special tool MB992110.

1. Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.