Hands Free Module (HFM)

B143B-MICROPHONE 1 CIRCUIT LOW







- When Monitored:
With the ignition on.

- Set Condition:
The Hands Free Module (HFM) detects a short to ground or open on the (X712) Microphone 1 IN (+) circuit.





1. CHECK FOR ACTIVE DTC

NOTE: Verify the connection of the Rearview Mirror harness connector.

1. Turn the ignition on.
2. With the scan tool, read the active DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- If the DTC is stored, check for an intermittent condition. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

2. INSIDE REARVIEW MIRROR




1. Turn the ignition off.
2. Disconnect the Inside Rearview Mirror harness connector.
3. Connect a jumper wire between the (X793) Microphone Feed and the (X712) Microphone 1 IN (+) circuits.
4. Turn the ignition on.
5. With the scan tool, read the DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 3

No

- Replace the Inside Rearview Mirror.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (X712) MICROPHONE 1 IN (+) CIRCUIT OPEN




1. Turn the ignition off.
2. Disconnect the Hands Free Module harness connector.
3. Measure the resistance of the (X712) Microphone 1 IN (+) circuit between the Inside Rearview Mirror and Hands Free Module harness connectors.

Is the resistance above 10K Ohms?

Yes

- Repair the (X712) Microphone 1 IN (+) circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. (X712) MICROPHONE 1 IN (+) CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Hands Free Module harness connector.
3. Measure the resistance between ground and the (X712) Microphone 1 IN (+) circuit.

Is the resistance below 10K Ohms?

Yes

- Repair the (X712) Microphone 1 IN (+) circuit for short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the Hands Free Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test.