P1021
DTC P1021: Engine Oil Control Valve CircuitEngine Oil Control Valve Circuit Part 1:
Engine Oil Control Valve Circuit Part 2:
CIRCUIT OPERATION
- The engine oil control valve power is supplied from the MFI relay (terminal No. 4).
- The PCM controls ground engine oil control valve by turning the power transistor in the PCM "ON" and "OFF".
TECHNICAL DESCRIPTION
- The engine oil control valve switches the cams to operate the MIVEC system in the low-speed or high-speed mode in accordance with the signals from the PCM.
DTC SET CONDITIONS Check Conditions
- Ignition switch: "ON"
- Battery positive voltage is higher than 10 volts.
- MIVEC operating in the low-speed mode.
Judgment Criteria
- The PCM terminal voltage of engine control valve circuit is less than 1.5 volts for 2 seconds.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Engine oil control valve failed.
- Open or shorted engine oil control valve circuit, or harness damage or connector damage.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991923: Power Plant ECU Check Harness
STEP 1. Check harness connector B-33 at the engine oil control valve for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 2. Check the engine oil control valve.
1. Disconnect the engine oil control valve connector B-33.
2. Measure the resistance between engine oil control valve side connector terminal No. 1 and No. 2.
Standard value: 6.9 - 7.9 Ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 6.9 and 7.9 Ohms [at 20 °C (68 °F)]?
YES: Go to Step 3.
NO: Replace the engine oil control valve. Then go to Step 12.
STEP 3. Measure the power supply voltage at engine oil control valve harness side connector B-33.
1. Disconnect the connector B-33 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 1 and ground.
- Voltage should be 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 4.
STEP 4. Check harness connector B-17X at MFI relay for damage.
Q: Is the harness connector in good condition?
YES: Repair harness wire between MFI relay connector B-17X (terminal No. 4) and engine oil control valve connector B-33 (terminal No. 1) because of open circuit or short circuit to ground. Then go to Step 12.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 5. Measure the power supply voltage at PCM connector B-23 by using power plant ECU check harness special tool MB991923.
1. Disconnect the all PCM connectors and connect power plant ECU check harness special tool MB991923 between the separated connectors.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 128 and ground.
- Voltage should be 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 8.
NO: Go to Step 6.
STEP 6. Check harness connector B-23 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 7.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 7. Check for open circuit and short circuit to ground between engine oil control valve connector B-33 (terminal No. 2) and PCM connector B-23 (terminal No. 128).
Q: Is the harness wire in good condition?
YES: Replace the PCM. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 8. Check harness connector B-23 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 9. Check for harness damage between MFI relay connector B-17X (terminal No. 4) and engine oil control valve connector B-33 (terminal No. 1).
Q: Is the harness wire in good condition?
YES: Go to Step 10.
NO: Repair it. Then go to Step 12.
STEP 10. Check for harness damage between engine oil control valve connector B-33 (terminal No. 2) and PCM connector B-23 (terminal No. 128).
Q: Is the harness wire in good condition?
YES: Go to Step 11.
NO: Repair it. Then go to Step 12.
STEP 11. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. After the DTC has been deleted, read the DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1021 set?
YES: Replace the PCM. Then go to Step 12.
NO: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.
STEP 12. Using scan tool MB991958, read the diagnostic trouble code (DTC).
1. Turn the ignition switch to the "ON" position.
2. After the DTC has been deleted, read the DTC again.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1021 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.