If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
OPERATION
If 4WD-ECU determines that the vehicle is used under some severe operational conditions (such as a long-time driving in 4WD on a sandy road, slushy road or road with deep snows or towing or long hill-climbing), 4WD-ECU detects the overload to the coupling. If abnormal overload is detected, 4WD-ECU interrupts the system to prevent it from being damaged.
DIAGNOSIS CODE SET CONDITIONS
If the following conditions are met, 4WD-ECU gradually switches the control from 4WD to 2WD, makes the drive system fluid temperature warning lamp illuminate, and sets the diagnosis code No. C145F.
4WD selector switch: 4WD
When the load to the electronic control coupling is large, the mode is switched to the 2WD mode.
PROBABLE CAUSES
Current trouble
The driving conditions are severe.
Electronic control coupling failure (clutch slippage)
4WD-ECU malfunction
Abnormality in ABS wheel speed signal
Abnormality in torque command value from the ASC-ECU
Past trouble
The past driving conditions were severe.
Electronic control coupling intermittent failure (clutch slippage)
Abnormality in ABS wheel speed signal
Abnormality in torque command value from the ASC-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 4.
Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting .) On completion, go to Step 2.
STEP 2. Check whether the diagnosis code is reset after repairing the CAN bus line.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code No. C145F set?
Go to Step 3.
This diagnosis is complete.
STEP 3. M.U.T.-III Diagnosis code of other systems
Check the following service data. (Refer to .)
Item 07: CAN system (ABS/ASC)
Item 16: FL wheel speed sensor
Item 17: FR wheel speed sensor
Item 18: RL wheel speed sensor
Item 19: RR wheel speed sensor
Q.
Is the diagnosis code set?
Troubleshoot the ABS system. (Refer to GROUP 35C - Troubleshooting .)
Go to Step 4.
STEP 4. M.U.T.-III actuator test
Perform the actuator test for the following items. (Refer to .)
Item 01: 4WD coupling control torque
Q.
Does the electronic control coupling transfer the torque correctly?
Go to Step 5.
Replace the electronic control coupling. (Refer to .) Then go to Step 6.
STEP 5. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code No. C145F set?
Replace 4WD-ECU. (Refer to .) Then go to Step 6.
The code may be set because of some severe operational conditions such as a long-time high speed driving or long hill-climbing in 4WD condition.
STEP 6. Check whether the diagnosis code is reset.
Go to Step 4.
Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting 
.) On completion, go to Step 2.