Inspection Procedure 1: M.U.T.-III communication with FCM/LDW/AHB system is impossible.


caution
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

COMMENTS ON TROUBLE SYMPTOM


When M.U.T.-III cannot communicate with the FCM/LDW/AHB system, the CAN bus lines, FCM/LDW/AHB-ECU power supply circuit system, earth, or FCM/LDW/AHB-ECU may be faulty.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE


STEP 1. Resistance measurement at FCM/LDW/AHB-ECU connector (GND terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the FCM/LDW/AHB-ECU connector (GND terminal) and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 3.

Go to Step 2.

STEP 2. Check of open circuit in GND line between FCM/LDW/AHB-ECU connector and body earth.


Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

Repair the connector(s) or wiring harness.

STEP 3. Voltage measurement at FCM/LDW/AHB-ECU connector (IG terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check the voltage between the FCM/LDW/AHB-ECU connector (IG terminal) and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 4.

Go to Step 5.

STEP 4. Retest the system.


Q. Does the security alarm work normally?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

Replace the FCM/LDW/AHB-ECU (Refer to ).

STEP 5. Check of short to earth, and open circuit in IG line between fusible link and FCM/LDW/AHB-ECU connector.


Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).

Repair the connector(s) or wiring harness.