Inspection Procedure 2: The FCM System cannot be Turned ON or OFF when the FCM and UMS ON/OFF Switch is Operated.

caution

If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).
When the hydraulic unit assembly (integrated with ASTC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G sensor.
Before replacing the ECU, ensure that the communication circuit is normal.
When the ACC/FCM-ECU is replaced, calibrate the radar (refer to ).

COMMENTS ON TROUBLE SYMPTOMS

The ACC/FCM-ECU has detected an abnormality.
The FCM and UMS ON/OFF switch circuit is short-circuited.
The FCM system cannot be turned ON under any of the conditions:

Transfer position: "4LLc"
Rear differential lock: ON
Hill descent control: ON
ASTC: OFF

PROBABLE CAUSES

Malfunction of the CAN bus line
Damaged wiring harness and connectors
Malfunction of the FCM and UMS ON/OFF switch
Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
Malfunction of the ACC/FCM-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.

Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 2.

STEP 2. M.U.T.-III data list.

Check the FCM system data list.

Press the FCM and UMS ON/OFF switch.

Item No.	Item name	Normal condition
20	FCM switch state	ON (the switch being pressed)

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 3.

STEP 3. M.U.T.-III data list for other system.

Check the ASTC system data list.

Press the FCM and UMS ON/OFF switch.

Item No.	Item name	Normal condition
32	FCM off switch	ON (the switch being pressed)

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 4.

STEP 4. FCM and UMS ON/OFF switch check.

Check the FCM and UMS ON/OFF switch.

Q. Is the check result normal?

	Go to Step 5.

	Replace the FCM and UMS ON/OFF switch.

STEP 5. Resistance measurement at FCM and UMS ON/OFF switch connector.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Measure the resistance between the FCM and UMS ON/OFF switch connector (earth terminal) and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

	Go to Step 7.

	Go to Step 6.

STEP 6. Check of open circuit in earth line between FCM and UMS ON/OFF switch connector and the body earth.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction).

	Repair the connector(s) or wiring harness.

STEP 7. Check of open circuit in FCSW line between hydraulic unit assembly (integrated with ASTC-ECU) connector and FCM and UMS ON/OFF switch connector.

Q. Is the check result normal?

	Replace the hydraulic unit assembly (integrated with ASTC-ECU).

	Repair the connector(s) or wiring harness.

STEP 8. Retest the system.

Check that the FCM system control operates normally.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction).

	Replace the ACC/FCM-ECU (Refer to ).