Code No. C145D: Wiring harness or coupling coil open circuit failure

caution

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 the current flowing in the electronic control coupling solenoid coil is smaller than the command value from 4WD-ECU, the system is deactivated.

DIAGNOSIS CODE SET CONDITIONS

If the following conditions are met when the system is activated, 4WD-ECU switches the control from 4WD to 2WD, flashes the 4WD/LOCK indicators alternately, and sets the diagnosis code No. C145D.

Sets the specified current command value to the electronic control coupling solenoid
Drive current value of the electronic control coupling solenoid: Deviated below from the normal current range

PROBABLE CAUSES

Current trouble

Open circuit inside the electronic control coupling solenoid
Damaged wiring harness and connectors

Open circuit between 4WD-ECU and the electronic control coupling solenoid

4WD-ECU internal error

Past trouble

Intermittent wiring harness or connector failure

note For diagnosis procedures, refer to "How to treat past trouble" (Refer to GROUP 00, How to Treat Past Trouble ).
Intermittent electronic control coupling failure (solenoid failure)

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 3.

	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 and hold there for 2 seconds.

(3)Fully depress the accelerator pedal, and maintain its position for 2 seconds.

note

The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.

(4)Check if the diagnosis code is set.

Q. Is the diagnosis code No. C145D set?

	Go to Step 3.

	This diagnosis is complete.

STEP 3. M.U.T.-III data list

Check the following service data (Refer to

Item 04: Desired current of coupling
Item 05: Monitored current of coupling

Q. Is the check result normal?

	Go to Step 10.

	Go to Step 4.

STEP 4. Check the following connector:

Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.

C-57 4WD-ECU connector
D-39 intermediate connector
F-26 electronic control coupling solenoid connector
C-27 intermediate connector

Q. Are the connectors and terminals in good condition?

	Go to Step 5.

	Repair the connector(s) or terminal(s). Then go to Step 11.

STEP 5. Wiring harness check

Check the wiring harness between the C-57 4WD-ECU connector and the F-26 electronic control coupling solenoid connector, and the wiring harness between the F-26 electronic control coupling solenoid connector and the F-26-1 electronic control coupling solenoid side connector for damage or other problem.

Q. Is the wiring harness in good condition?

	Go to Step 6.

	Repair damage or other problem in the wiring harness. Then go to Step 11.

STEP 6. Resistance measurement between electronic control coupling solenoid connector (coupling side) terminals

Disconnect the F-26-1 connector, and measure the resistance value between the connector terminals on the electronic control coupling side.

Standard value: 2.2 - 4.0 Ω

Q. Is the measured resistance value within the standard value range?

	Go to Step 7.

	Replace the electronic control coupling (Refer to ). Then go to Step 11.

STEP 7. Voltage measurement at the 4WD-ECU connector

(1)Disconnect the C-57 4WD-ECU connector.

(2)Measure the voltage between the C-57 wiring harness side connector terminals No.3, No.4 (ignition switch "ON") and the body earth.
OK: System voltage

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 9.

STEP 8. Wiring harness check

Check the wiring harness between the C-57 4WD-ECU connector (terminal No.10) and the body earth for damage or other problem.

Q. Is the wiring harness in good condition?

	Go to Step 10.

	Repair the wiring harness. Then go to Step 11.

STEP 9. Wiring harness check

note

Prior to the wiring harness inspection, check the C-309 and C-315 ETACS-ECU connectors, and repair if necessary.

Check the wiring harness between the C-57 4WD-ECU connector (terminal No.3) and the fusible link No. 34, and the wiring harness between the C-57 4WD-ECU connector [terminal No.4 (ignition switch "ON")] and the fusible link No. 34 for damage or other problem.

Q. Is the wiring harness in good condition?

	Go to Step 10.

	Repair the wiring harness. Then go to Step 11.

STEP 10. 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 and hold there for 2 seconds.

(3)Fully depress the accelerator pedal, and maintain its position for 2 seconds.

note

The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.

(4)Check if the diagnosis code is set.

Q. Is the diagnosis code No. C145D set?

	Replace 4WD-ECU (Refer to ). Then go to Step 11 .

	The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 11. 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 and hold there for 2 seconds.

(3)Fully depress the accelerator pedal, and maintain its position for 2 seconds.

note

The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.

(4)Check if the diagnosis code is set.

Q. Is the diagnosis code No. C145D set?

	Diagnose again from Step 1.

	This diagnosis is complete.

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