B125A

DTC B125A

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC B125A 02
- Antenna Signal Circuit Short to Ground

DTC B125A 04
- Antenna Signal Circuit Open Circuit

Diagnostic Fault Information






Circuit/System Description

The AM/FM antenna is part of the multi-band antenna is located on the roof of the vehicle. The radio provides battery voltage to the AM/FM amplifier in the antenna base using the center conductor of the antenna coaxial cable. When a 12 V signal is seen by the amplifier, both AM and FM signals are amplified.

Conditions for Running the DTC

* Vehicle in Service Mode.
* Battery voltage must be between 9-16 V.

Conditions for Setting the DTC

B125A 02

The radio detects a short to ground in the antenna signal circuit center conductor.

B125A 04

The radio detects an open in the antenna signal circuit center conductor.

Action Taken When the DTC Sets

Radio reception may be poor or not available.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clears after 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

Radio/Navigation System Schematics Radio/Navigation System Schematics
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation

Radio/Audio System Description and Operation Radio/Audio System
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

Vehicle in Service Mode, radio ON, tune to a strong AM or FM station. Verify that the AM or FM reception is clear.

Circuit/System Testing

1. Vehicle OFF, disconnect the radio antenna coax from the A11 radio and the T4G antenna.
2. Test for infinite resistance between the antenna coax center terminal and ground.

• If less than the specified value, replace the antenna coax.

3. Test for infinite resistance between the coax center terminal and the outer shield.

• If less than the specified value, replace the antenna coax.

4. Test for less than 5 ohm on the antenna coax center circuit from end to end.

• If greater than the specified range, replace the antenna coax.

5. Vehicle in Service Mode, test for less than 1 V between the antenna coax center terminal and ground.

• If greater than the specified range, replace the antenna coax.

6. Connect the antenna coax to the A11 radio. Test for 12-15 V between the antenna coax center terminal and ground at the T4G antenna connector.

• If not within the specified range, replace the A11 radio.

7. If all circuits test normal, replace the T4G antenna.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Radio Antenna Base Replacement Radio Antenna Base Replacement
* Control Module References Programming and Relearning for radio replacement, programming and setup