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 antenna amplifier receives both AM and FM signals from the rear glass antenna. The radio antenna amplifier is enabled when the radio is turned on. The radio provides battery voltage to the antenna amplifier using the center conductor of the antenna coaxial cable. When a 12 V signal is seen by the module on the center conductor of the antenna coax, both AM and FM signals are amplified.
Conditions for Running the DTC
* Ignition ON.
* 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 Connector End Views By Name
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
Ignition ON, A11 radio ON, tune to a strong AM or FM station. Verify that the AM or FM reception is clear.
Circuit/System Testing
1. Ignition OFF, disconnect the radio antenna coax from the A11 radio and from the radio antenna amplifier.
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 less than 5 ohms on the antenna coax center circuit from end to end.
• If greater than the specified range, replace the antenna coax.
4. Ignition ON, test for less than 1 V between the antenna coax center terminal and ground.
• If greater than the specified range, replace the antenna coax.
5. Test for infinite resistance between the coax center terminal and the outer shield.
• If less than the specified value, 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 radio antenna amplifier connector.
• If not within the specified range, replace the A11 radio.
7. If all circuits test normal, replace the radio antenna amplifier.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Radio Antenna Amplifier Replacement Radio Antenna Amplifier Replacement
* Control Module References Programming and Relearning for radio replacement, setup, and programming