Inspection Procedure 7

Inspection Procedure 7: Check the hands free module power supply circuit.

CAUTION: Before replacing the module, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.

Hands Free Module Power Supply Circuit (Part 1):

Hands Free Module Power Supply Circuit (Part 2):

CIRCUIT OPERATION
The power supply to the hands free module is provided by the fusible link (36).

TECHNICAL DESCRIPTION (COMMENT)
If the hands free cellular phone system don't work, power supply and ground system to the hands free module, or the hands-free module itself may be defective.

TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- The hands-free module may be defective

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check hands free module connector C-110 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is hands-free module connector C-110 in good condition?

YES : Go to Step 2.

NO : Repair or replace the damaged component.

STEP 2. Check the ground circuit to the hands-free module. Measure the resistance at hands free module connector C-110.

1. Disconnect hands free module connector C-110, and measure at the wiring harness side.







2. Measure the resistance value between terminal 15 and ground.

OK: The resistance should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES : Go to Step 4.

NO : Go to Step 3.

STEP 3. Check the wiring harness between hands-free module connector C-110 (terminal 15) and ground.

- Check the ground wire for open circuit.

Q: Is the wiring harness between hands free module connector C-110 (terminal 15) and ground in good condition?

YES : Replace the hands free module. The system should communicate with the hands free module normally.

NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

STEP 4. Check the power supply circuit to the hands-free module. Measure the voltage at hands-free module connector C-110.

1. Disconnect hands free module connector C-110, and measure the voltage available at the hands-free module side of the connector.







2. Measure the voltage between terminal 13 and ground.

OK: The voltage should measure approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES : Replace the hands free module. The system should communicate with the hands-free module normally.

NO : Go to Step 5.

STEP 5. Check the wiring harness between hands-free module connector C-110 (terminal 13) and fusible link (36).

- Check the power supply line for open circuit and short circuit.

NOTE: Also check ETACS-ECU connectors C-307 and C-317 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-307 or C-317 is damaged, repair or replace the damaged component(s) as described.

Q: Is the wiring harness between hands-free module connector C-110 (terminal 13) and fusible link (36) in good condition?

YES : Replace the hands-free module. The system should communicate with the hands-free module normally.

NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.