Inspeciton Procedure 7: Check the hands-free-ECU power supply circuit.

caution

Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.

CIRCUIT OPERATION

The power supply to the hands-free-ECU is provided by the fusible link (34).
If the power supply system from the battery is defective, the system operates by the power supply from the ignition switch (IG1).

TECHNICAL DESCRIPTION (COMMENT)

If the hands-free cellular phone system don’t work, power supply and ground system to the hands-free-ECU, or the hands-free-ECU itself may be defective.

PROBABLE CAUSES

Damaged harness wires and connectors
Malfunction of the hands-free-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-122 hands-free-ECU connector

Q. Is the check result normal?

	Go to Step 2.

	Repair the defective connector.

STEP 2. Resistance measurement at C-122 hands-free-ECU connector.

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

(2)Check the continuity between terminal 15 and ground.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

	Go to Step 4.

	Go to Step 3.

STEP 3. Check the wiring harness between C-122 hands-free-ECU connector terminal No.15 and body earth.

Q. Is the check result normal?

	Replace the hands-free-ECU. The system should communicate with the hands-free-ECU normally.

	Repair the wiring harness.

STEP 4. Check the wiring harness between C-122 hands-free-ECU connector terminal No.13 and fusible link (34).

note

Prior to the wiring harness inspection, check C-307 and C-317 ETACS-ECU connector, and repair if necessary.

Q. Is the check result normal?

	Replace the hands-free-ECU. The system should communicate with the hands-free-ECU normally.

	Repair the wiring harness.