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DTC U011B: Valve Lift ECU Time-out
 
 
caution
  • Before replacing the ECU, make sure that the communication circuit is operating normally.
 
 
CIRCUIT OPERATION
  • Power is supplied to the valve left ECU terminal BAT1 from the engine control relay.
  • The ECM terminal LCAH and LCAL communicates with the valve lift ECU terminal LCAH and LCAL via VLC-CAN.
 
 
DESCRIPTIONS OF MONITOR METHODS
There is no data from valve lift ECU for the specified time. (Valve lift ECU also detect communication error with ECM.)
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable

 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Condition
  • Battery positive voltage is between 10 and 16.5 volts.
Judgment Criterion
  • Unable to receive valve lift ECU signals through the VCL-CAN for 4 seconds.
 
 
COMMENT
Current Trouble
  • Some of the possible causes are a harness or connector damage between the ECM and the valve lift ECU on the VCL-CAN, a failure in the valve lift ECU power supply system, a failure in the valve lift ECU, or a failure in the ECM.
Past Trouble
  • Proceed to troubleshoot based on a harness or connector damage on the VCL-CAN between the ECM and valve lift ECU, and a failure in the valve lift ECU power supply system. Refer to "How to cope with past trouble" (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, deenergizes the variable valve lift control motor.
 
 
OBD-II DRIVE CYCLE PATTERN
  • None.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be stored are:)
  • VCL-CAN line harness damage or connector damage.
  • Valve lift ECU failed.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle Communication Interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite Main Harness A
  • MB992747: V.C.I.-Lite USB Cable Short
  • MB992748: V.C.I.-Lite USB Cable Long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Measure the sensor supply voltage at valve lift ECU harness side connector.
(1) Disconnect the valve lift ECU connector and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal BAT1 line and ground.
  • Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 2.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in BAT1 line between MFI relay connector and valve lift ECU connector. Then go to Step 10.
 
STEP 2. Check of harness damage in BAT1 line between MFI relay connector and valve lift ECU connector.
Is the harness wire in good condition?
Go to Step 3.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 3. Check the continuity at valve lift ECU harness side connector.
(1) Disconnect the valve lift ECU connector and measure at the harness side.
(2) Measure the continuity between terminal GND line and ground
  • Continuity (2 ohms or less)
Does continuity exist?
Go to Step 4.
Repair or replace the connector(s), or check and repair the harness of open circuit and harness damage in GND line between valve lift ECU connector and ground. Then go to Step 10.
 
STEP 4. Inspection of terminal resistors in the ECM VCL-CAN.
cautionA digital multimeter should be used. (Refer to GROUP 54C - Service Precautions ).
(1) Disconnect ECM connector and measure at ECM side.
(2) Measure the resistance between ECM connector terminal LCAH and terminal LCAL.
Standard value: 100 - 140 ohms [at 20°C (68°F)]
Is the measured resistance between 100 and 140 ohms [at 20°C (68°F)]?
Go to Step 5.
Replace the ECM (Refer to Removal and Installation ). Then go to Step 10.
 
STEP 5. Inspection of terminal resistors in the valve lift ECU VCL-CAN.
cautionA digital multimeter should be used. (Refer to GROUP 54C - Service Precautions ).
(1) Disconnect valve lift ECU connector and measure at valve lift ECU side.
(2) Measure the resistance between the valve lift ECU connector terminal LCAH and terminal LCAL.
Standard value: 100 - 140 ohms [at 20°C (68°F)]
Is the measured resistance between 100 and 140 ohms [at 20°C (68°F)]?
Go to Step 6.
Replace the valve lift ECU. Then go to Step 10.
 
STEP 6. Check of short to power supply, short to ground, open circuit and harness damage in LCAH line between ECM connector and valve lift ECU connector.
Is the harness wire in good condition?
Go to Step 7.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 7. Check of short to power supply, short to ground, open circuit and harness damage in LCAL line between ECM connector and valve lift ECU connector.
Is the harness wire in good condition?
Go to Step 8.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 8. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) After the MFI-DTC has been deleted, read the MFI-DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U011B stored?
Replace the valve lift ECU. Then go to Step 9.
It can be assumed that this malfunction is intermittent of VCL-CAN between ECM and valve lift ECU. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 9. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the MFI-DTC has been deleted, read the MFI-DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U011B stored?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 10.
It can be assumed that this malfunction is intermittent of VCL-CAN between ECM and valve lift ECU. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 10. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) After the MFI-DTC has been deleted, read the MFI-DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U011B stored?
Retry the troubleshooting.
The inspection is complete.