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 ECM
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 ECM
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 ECM
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.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Check harness connector B-124 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-124.
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-124.
1. Disconnect the connector B-124 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-12X at MFI relay for damage.
Q: Is the harness connector in good condition?
YES: Check harness connector C-105 at intermediate connector for damage and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector is in good condition, repair harness wire between MFI relay connector B-12X (terminal No.4) and engine oil control valve connector B-124 (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 ECM connector C-139
1. Do not disconnect the connector C-139
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No.95 and ground by backprobing.
- 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 C-139 at ECM
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-124 (terminal No.2) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 8. Check harness connector C-139 at ECM
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-12X (terminal No. 4) and engine oil control valve connector B-124 (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-124 (terminal No.2) and ECM connector C-139
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 ECM or 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 - How to Cope with Intermittent Malfunctions.
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.