B143B-MICROPHONE 1 CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.

When Monitored:
With the ignition on.
Set Condition:
The Radio detects a short to ground or open on the (X712) Microphone 1 IN (+) circuit.

Possible Causes
(X712) MICROPHONE 1 IN (+) CIRCUIT OPEN
(X712) MICROPHONE 1 IN (+) CIRCUIT SHORTED TO GROUND
(X793) MICROPHONE FEED CIRCUIT OPEN
HANDS FREE MICROPHONE
RADIO

1. CHECK FOR ACTIVE DTC

NOTE: Verify the connection of the Hands Free Microphone harness connector.

1.	Turn the ignition on.

2.	With the scan tool, read the active DTCs.

Does the scan tool display B143B-MICROPHONE 1 CIRCUIT LOW as active?

Yes

Go To 2

Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

2. CHECK FOR VOLTAGE AT THE HANDS FREE MICROPHONE

1.	Turn the ignition off.

2.	Disconnect the Hands Free Microphone harness connector.

3.	Turn the ignition on.

4.	Measure the voltage between the (X793) Microphone Feed circuit and ground.

Is the voltage above 10.0 volts?

Yes

Go To 5

Go To 3

3. CHECK FOR VOLTAGE AT THE RADIO

1.	While back probing, measure the voltage between the (X793) Microphone Feed circuit and ground at the Radio C1 harness connector.

NOTE: The graphic shows the connector for reference only. Back probe the harness connector.

Is the voltage above 10.0 volts?

Yes

Repair the (X793) Microphone Feed circuit for an open.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

Go To 4

4. RESTORE THE VEHICLE CONFIGURATION

1.	With the scan tool, restore the vehicle configuration.

2.	Turn the ignition off, then back on.

3.	With the scan tool, read the active DTCs.

Does the scan tool display B143B-MICROPHONE 1 CIRCUIT LOW as active?

Yes

Replace the Radio in accordance with the Service Information.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

5. CHECK THE HANDS FREE MICROPHONE

1.	Turn the ignition off.

2.	Disconnect the Hands Free Microphone 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.

NOTE: DTC B143C-MICROPHONE 1 CIRCUIT HIGH should display as active as a result of this test.

Does the scan tool display B143B-MICROPHONE 1 CIRCUIT LOW as active?

Yes

Go To 6

Replace the Hands Free Microphone in accordance with the Service Information.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

6. CHECK FOR THE (X712) MICROPHONE 1 IN (+) CIRCUIT OPEN

1.	Turn the ignition off.

2.	Disconnect the Radio C1 harness connector.

3.	Measure the resistance of the (X712) Microphone 1 IN (+) circuit between the Hands Free Microphone and Radio C1 harness connectors.

Is the resistance above 10K Ohms?

Yes

Repair the (X712) Microphone 1 IN (+) circuit for an open.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

Go To 7

7. CHECK FOR THE (X712) MICROPHONE 1 IN (+) CIRCUIT SHORTED TO GROUND

1.	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. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

Replace the Radio in accordance with the Service Information.
Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).

B143B-MICROPHONE 1 CIRCUIT LOW

Possible Causes