Radio Poor Reception
Radio Poor Reception
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 multi-band antenna is located on the roof of the vehicle. The radio antenna is enabled when the radio is turned on. The radio provides battery voltage to the antenna using the center conductor of the antenna coaxial cable. When a 12 V signal is seen 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 Sunshade - Left Front
Description and Operation
Radio/Audio System Description and Operation (with Monochrome Display) Radio/Audio System Description and Operation (with Monochrome Display)Radio/Audio System Description and Operation (with Color Display) Radio/Audio System Description and Operation (with Color Display)
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 Control Module References 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 cable from the A11 radio and from the T4G antenna.
2. Verify the antenna coax cable passes the coax cable component test. Refer to Component Testing.
• If the coax cable does not pass the test
Replace the antenna coax cable
• If the coax cable passes the test
3. Connect the radio antenna coax cable to the A11 radio.
4. Ignition ON, A11 radio ON. Verify a test lamp illuminates between the antenna coax cable center terminal and ground at the T4G antenna.
• If the test lamp does not illuminate
replace the A11 radio.
• If the test lamp illuminates
5. Test or replace the T4G antenna.
Component Testing
Caution: Refer to Test Probe Caution Test Probe Caution.
Note: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.
To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.
Coax Cable Test
1. Ignition OFF, disconnect the coax cable at both components.
2. Test for less than 5 ohms between coax cable center terminal end to end.
• If 5 ohms or greater
Replace the coax cable
• If less than 5 ohms
3. Test for less than 5 ohms between the coax cable outer shield end to end.
• If 5 ohms or greater
Replace the coax cable
• If less than 5 ohms
4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.
• If less than infinite resistance
Replace the coax cable
• If infinite resistance
5. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Radio Antenna Base Replacement Radio Antenna Base Replacement
* Control Module References Control Module References for radio replacement, programming, and setup.