Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Antenna Enable Signal | 1 | 1 | -- | -- |
1. No or poor AM reception, amplifier inoperative (if equipped) | ||||
Circuit/System Description
AM and FM radio reception is dependent on the following components:
| • | Radio |
| • | Radio antenna |
| • | Coax cable between the radio and the radio antenna |
The multi-band antenna is located on the roof of the vehicle. A switched B+ output from the radio antenna enable circuit is used to power the AM/FM portion of this antenna. The antenna enable circuit is also used to control the power state of the amplifier (if equipped) and the rear seat entertainment video display (if equipped).
Diagnostic Aids
Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related. Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio reception may also be influenced by items within the vehicle, but are not part of the radio system. Such examples are aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system.
AM reception is highly dependent on the antenna receiving battery voltage from the radio. The antenna has a built in antenna amplifier that boosts both AM and FM reception. If the antenna does not receive battery voltage, the radio will still receive FM stations but AM stations will not be received.
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
Radio/Audio System Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- Inspect the antenna for proper mounting or physical damage.
- Radio ON, tune to several known strong FM, AM, and XM (if equipped) stations, and play a known good CD. Verify clear sound from all sources.
| ⇒ | If damage is found, repair or replace as necessary |
| ⇒ | If audio quality is poor from all sources, refer to Speakers Inoperative - One or More. |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the antenna.
- Radio ON, verify that a test lamp illuminates between the signal circuit terminal 1 and ground.
- Ignition OFF, disconnect the radio antenna coax cable from the radio and the radio antenna.
- Test for infinite resistance between the antenna coax center terminal and ground.
- Test for less than 10 Ω on the antenna coax center terminal from end to end.
- Test for less than 10 Ω on the antenna coax outer shield from end to end.
- Test for infinite resistance between the coax center terminal and the outer shield.
- If all circuits test normal, replace the radio antenna.
| ⇒ | If test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio. |
| ⇒ | If less than the specified value, replace the antenna coax. |
| ⇒ | If greater than the specified range, replace the antenna coax. |
| ⇒ | If greater than the specified range, replace the antenna coax. |
| ⇒ | If less than the specified value, replace the antenna coax. |
| ⇒ | If reception is still poor, replace the radio. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for Radio replacement, setup and programming |
