[Previous][Next]
Inspection Procedure 1: Check the hands free module power supply circuit.
 
 
cautionBefore replacing the module, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
CIRCUIT OPERATION
  • The hands free module is energized via the fusible link.
  • The ACC signal is received through the radio and CD player.
 
 
 
TROUBLESHOOTING HINTS
  • The hands free module may be defective
  • The radio and CD player may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
 
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Resistance measurement at hands free module connector (GND terminal).
(1) Disconnect hands free module connector, and measure at the wiring harness side.
(2) Check the continuity between GND terminal and ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 3
Go to Step 2
 
STEP 2. Check of open circuit in GND line between hands free module connector and ground.
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 hands free module connector (+B terminal).
(1) Disconnect hands free module connector, and measure at the wiring harness side.
(2) Measure the voltage between +B terminal and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 5
Go to Step 4
 
STEP 4. Check of short to power supply, short to ground, and open circuit in +B line between fusible link and hands free module connector.
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 5. Voltage measurement at hands free module connector (ACC terminal).
(1) Disconnect hands free module connector, and measure at the wiring harness side.
(2) Turn the ignition switch to "ACC" position.
(3) Measure the voltage between ACC terminal and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Replace the hands free module.
Go to Step 6
 
STEP 6. Check of short to power supply, short to ground, and open circuit in ACC line between hands free module connector and radio and CD player connector.
Is the check result normal?
Replace the radio and CD player.
Repair the connector(s) or wiring harness.