Inspection Procedure 2: Power supply to the BSW-ECU (slave) fails (Cannot communicate with BSW-ECU (slave) using the M.U.T.-III.)

caution

When replacing the ECU, always check that the communication circuit is normal.

COMMENTS ON TROUBLE SYMPTOM

BSW-ECU (slave) is communicating with M.U.T.-III via CAN. Therefore, communication error of BSW-ECU (slave) is suspected.

note

Check whether the BSW-ECU (master) sets diagnosis code No. C2332. Then follow this diagnosis.

PROBABLE CAUSES

Malfunction of the power supply and the earth of BSW-ECU (slave)
Malfunction of the BSW-ECU (slave)

DIAGNOSIS PROCEDURE

STEP 1. Resistance measurement at BSW-ECU (slave) connector terminal GND.

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

(2)Measure the resistance between the BSW-ECU (slave) connector terminal GND and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 2

Repair the connector(s) or wiring harness.

STEP 2. Voltage measurement at BSW-ECU (slave) connector terminal IG.

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

(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.

(3)Check the voltage between the BSW-ECU (slave) connector terminal IG and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3

Repair the connector(s) or wiring harness.

STEP 3. Retest the system

Check if M.U.T.-III can communicate with the BSW-ECU (slave).

Q. Is the check result normal?

Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to cope with Intermittent Malfunction).

Replace the BSW-ECU (slave).