Code No. U011B: Valve Lift ECU Time-out

caution

Replace ECU after certainly confirming that the communication circuits are normal.

OPERATION

Power is supplied to the valve left ECU connector terminal BAT1 from the engine control relay connector terminal.
The engine-ECU connector terminal LCAH and LCAL communicates with the valve lift ECU connector terminal LCAH and LCAL via VLC-CAN.

TROUBLE JUDGMENT

Check Conditions

After 2 seconds since the ignition switch is turned ON.
Battery positive voltage is more than 10 V and is less than 16.5 V.
After 2 seconds since the battery voltage has reached 10 V or more.

Judgement Criterion

The engine-ECU has received malfunction from the valve lift ECU via VCL-CAN for at least four seconds.
The valve lift ECU has detected any of the malfunctions below:

The system remains received no signals.
The received target control angles remains out of a predetermined range.

COMMENTS ON TROUBLE SYMPTOM

Current malfunction

The failure is possibly caused by malfunction of the harness and connector in CAN bus line between engine-ECU and valve lift ECU, by malfunction in the power supply system of valve lift ECU, in valve lift ECU itself, in engine-ECU.

Past malfunction

Proceed with troubleshooting focusing on malfunction of the harness and connector in CAN bus line between engine-ECU and valve lift ECU and malfunction in the power supply system of valve lift ECU. For diagnosis procedure, refer to how to cope with past malfunctions. (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble ).

FAIL-SAFE AND BACKUP FUNCTION

The valve lift is fixed to maximum. Otherwise, deenergises the motor.
V.V.T. phase angle is set to most retarded position.

PROBABLE CAUSES

Failed harness and connector
Failed valve lift ECU
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at valve lift ECU connector.

Disconnect connector, and measure at harness side.
Voltage between terminal BAT1 and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 2

	Repair or replace the connector, or check and repair harness between engine control relay connector terminal and valve lift ECU connector terminal BAT1, go to Step 10. Check power supply line for open/short circuit.

STEP 2. Check harness between engine control relay connector terminal and valve lift ECU connector terminal BAT1.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the connector, or repair the damaged harness wire, go to Step 10.

STEP 3. Perform resistance measurement at valve lift ECU connector.

Disconnect connector, and measure at harness side.
Resistance between terminal GND and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace the connector, or check and repair the harness between the valve lift ECU connector terminal GND and body earth, go to Step 10. Check earthing line for open circuit and damage.

STEP 4. Inspection of terminal resistors in the engine-ECU VCL-CAN.

caution

A digital multimeter should be used. (Refer to GROUP 54C - Service Precautions

Disconnect engine-ECU connector, and then measure at the equipment side.
Resistance between terminal LCAH and LCAL.

OK: 100 - 140 Ω (at 20°C)

Q. Is the check result normal?

	Go to Step 5.

	Replace the engine-ECU, go to Step 10.

STEP 5. Inspection of terminal resistors in the valve lift ECU VCL-CAN.

caution

A digital multimeter should be used. (Refer to GROUP 54C - Service Precautions

Disconnect valve lift ECU connector, and then measure at the equipment side.
Resistance between terminal LCAH and LCAL.

OK: 100 - 140 Ω (at 20°C)

Q. Is the check result normal?

	Go to Step 6.

	Replace the valve lift ECU, go to Step 10.

STEP 6. Check harness between engine-ECU connector terminal LCAH and valve lift ECU connector terminal LCAH.

Check signal line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 7.

	Repair or replace the connector, or repair the damaged harness wire, go to Step 10.

STEP 7. Check harness between engine-ECU connector terminal LCAL and valve lift ECU connector terminal LCAL.

Check signal line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 8.

	Repair or replace the connector, or repair the damaged harness wire, go to Step 10.

STEP 8. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	After replacing valve lift ECU, go to Step 9

	Intermittent malfunction in CAN bus line between engine-ECU and valve lift ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 9. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	After replacing engine-ECU, go to Step 10

	Intermittent malfunction in CAN bus line between engine-ECU and valve lift ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 10. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	Go to Step 1.

	Check end.