Code No. P1021: Oil Control Valve Circuit

OPERATION

Power is supplied to the oil control valve (terminal No. 1) from the engine control relay (terminal No. 1).

The engine-A/T-ECU (terminal No. 95) makes the power transistor in the unit be in "ON" position, and that makes currents go on the oil control valve (terminal No. 2).

FUNCTION

The 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 engine-A/T-ECU.

TROUBLE JUDGMENT

Check Conditions

Ignition switch is "ON" position

Battery positive voltage is 10 - 16.5 V.

MIVEC operating in the low-speed mode.

Judgment Criterion

The engine-A/T-ECU terminal voltage of oil control valve circuit is less than 1.5 V for 2 seconds.

PROBABLE CAUSE

Failed oil control valve

Open/short circuit in oil control valve circuit or loose connector contact

Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-117oil control valve connector

Q: Is the check result normal?

YES: Go to Step 2

.
NO: Repair.

STEP 2: Perform resistance measurement at B-117 oil control valve connector.

Disconnect connector, and measure at oil control valve side.

Resistance between terminal No. 1 and No. 2.

OK: 6.9 - 7.9 Ω (at 20°C)

Q: Is the check result normal?

YES: Go to Step 3

.
NO: Replace oil control valve.

STEP 3. Perform voltage measurement at B-117 oil control valve connector.

Disconnect connector, and measure at harness side.

Ignition switch: ON

Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 5

.
NO: Go to Step 4

STEP 4. Connector check: B-17X engine control relay connector

Q: Is the check result normal?

YES:

Check intermediate connector C-17, and repair if necessary. If intermediate connector is normal, check and repair harness between B-117 (terminal No. 1) oil control valve connector and B-17X (terminal No. 1) engine control relay connector.

Check power line for open/short circuit.

NO: Repair.

STEP 5. Perform voltage measurement at C-137 engine-A/T-ECU connector.

Disconnect connector, and measure at harness side.

Ignition switch: ON

Voltage between terminal No. 95 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 7

.
NO: Go to Step 6

STEP 6. Connector check: C-137 engine-A/T-ECU connector

Q: Is the check result normal?

YES:

Check and repair harness between B-117 (terminal No. 2) oil control valve connector and C-137 (terminal No. 95) engine-A/T-ECU connector.

Check output line for open/short circuit.

NO: Repair.

STEP 7. Connector check: C-137 engine-A/T-ECU connector

Q: Is the check result normal?

YES: Go to Step 8

.
NO: Repair.

STEP 8. Check harness between B-117 (terminal No. 2) oil control valve connector and C-137 (terminal No. 95) engine-A/T-ECU connector.

Check output line for damage.

Q: Is the check result normal?

YES: Go to Step 9

.
NO: Repair.

STEP 9. Check harness between B-117 (terminal No. 1) oil control valve connector and B-17X (terminal No. 1) engine control relay connector.

NOTE: Before checking harness, check intermediate connector C-17, and repair if necessary.

Check power supply line for damage.

Q: Is the check result normal?

YES: Go to Step 10

.
NO: Repair.

STEP 10. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES: Replace engine-A/T-ECU.
NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points


Code No. P1021: Oil Control Valve Circuit

OPERATION Power is supplied to the oil control valve (terminal No. 1) from the engine control relay (terminal No. 1). The engine-A/T-ECU (terminal No. 95) makes the power transistor in the unit be in "ON" position, and that makes currents go on the oil control valve (terminal No. 2).
FUNCTION The 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 engine-A/T-ECU.
TROUBLE JUDGMENT Check Conditions Ignition switch is "ON" position Battery positive voltage is 10 - 16.5 V. MIVEC operating in the low-speed mode. Judgment Criterion The engine-A/T-ECU terminal voltage of oil control valve circuit is less than 1.5 V for 2 seconds.
PROBABLE CAUSE Failed oil control valve Open/short circuit in oil control valve circuit or loose connector contact Failed engine-A/T-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Connector check: B-117oil control valve connector
	Q: Is the check result normal? YES: Go to Step 2 . NO: Repair.
	STEP 2: Perform resistance measurement at B-117 oil control valve connector.
	Disconnect connector, and measure at oil control valve side. Resistance between terminal No. 1 and No. 2. OK: 6.9 - 7.9 Ω (at 20°C) Q: Is the check result normal? YES: Go to Step 3 . NO: Replace oil control valve.
	STEP 3. Perform voltage measurement at B-117 oil control valve connector.
	Disconnect connector, and measure at harness side. Ignition switch: ON Voltage between terminal No. 1 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 5 . NO: Go to Step 4 .
	STEP 4. Connector check: B-17X engine control relay connector
	Q: Is the check result normal? YES: Check intermediate connector C-17, and repair if necessary. If intermediate connector is normal, check and repair harness between B-117 (terminal No. 1) oil control valve connector and B-17X (terminal No. 1) engine control relay connector. Check power line for open/short circuit. NO: Repair.
	STEP 5. Perform voltage measurement at C-137 engine-A/T-ECU connector.
	Disconnect connector, and measure at harness side. Ignition switch: ON Voltage between terminal No. 95 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 7 . NO: Go to Step 6 .
	STEP 6. Connector check: C-137 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Check and repair harness between B-117 (terminal No. 2) oil control valve connector and C-137 (terminal No. 95) engine-A/T-ECU connector. Check output line for open/short circuit. NO: Repair.
	STEP 7. Connector check: C-137 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Go to Step 8 . NO: Repair.
	STEP 8. Check harness between B-117 (terminal No. 2) oil control valve connector and C-137 (terminal No. 95) engine-A/T-ECU connector.
	Check output line for damage. Q: Is the check result normal? YES: Go to Step 9 . NO: Repair.
	STEP 9. Check harness between B-117 (terminal No. 1) oil control valve connector and B-17X (terminal No. 1) engine control relay connector.
	NOTE: Before checking harness, check intermediate connector C-17, and repair if necessary. Check power supply line for damage. Q: Is the check result normal? YES: Go to Step 10 . NO: Repair.
	STEP 10. Check the trouble symptoms. Q: Does trouble symptom persist? YES: Replace engine-A/T-ECU. NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).