Radio Poor Reception

RADIO POOR RECEPTION

DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

CIRCUIT/SYSTEM TESTING (WITH ANTENNA MAST)

IMPORTANT: Perform the Audio System Troubleshooting Hints to properly identify the customers concern before using this diagnostic. Audio System Troubleshooting Hints

1. With the ignition OFF, disconnect the antenna cable from the radio. With a DMM, verify there is less than 0.20 ohms between the negative battery cable and the coaxial cable metal outer shield.
- If greater than 0.20 ohms, test the antenna mast base for proper ground to the body. If antenna is properly grounded replace the antenna coax cable.
2. Disconnect the coax cable from the antenna mast. With a DMM, verify there is less than 3.5 ohms between the radio end coaxial cable conductor and the antenna end coaxial cable conductor.
- If greater than 3.5 ohms, replace the coax cable.
- If no problems are found with the coax cable or the grounding of the antenna mast replace the radio.

CIRCUIT/SYSTEM TESTING (WITH SIDE REAR GLASS ANTENNA GRID)

IMPORTANT: Perform the Audio System Troubleshooting Hints to properly identify the customers concern before using this diagnostic. Audio System Troubleshooting Hints

1. With the ignition OFF, disconnect the antenna cable from the radio. With a DMM, verify there is less than 0.20 ohms between the negative battery cable and the coaxial cable metal outer shield.
- Inspect the antenna module ground and bracket for a proper connection. If greater than 0.20 ohms, test the antenna module ground for an open or short to power. If antenna module and bracket is properly grounded replace the antenna coax cable.
2. Disconnect the coax cable from the antenna module bracket. With a DMM, verify there is less than 3.5 ohms between the radio end coaxial cable conductor and the antenna module end coaxial cable conductor.
- If greater than 3.5 ohms, replace the coax cable.
3. Disconnect the antenna module harness connector. Turn ON the ignition and the radio. With a DMM verify the remote enable signal circuit receives B+.
- If B+ is not present on the remote enable circuit with the ignition and radio ON, test or repair open or short to ground on the remote enable circuit. If open or short to ground can not be found, replace the radio.
4. Reconnect the coax cable to the radio and the antenna module. Reconnect the antenna module harness connector. Turn ON the ignition and radio. With the scan tool observe and record the signal strength dBuV in the radio data list. Disconnect the coax cable from the radio antenna module bracket and observe the dBuV for a drop in signal strength.
- If the dBuV displayed on the scan tool did not drop signal strength with the antenna module unplugged, replace the antenna module.
5. Test for continuity of the individual lines of the antenna grid. Inspect for a improper button connection at the antenna connector (side rear glass). With a DMM, verify every antenna grid line has continuity end to end.
- If there is no continuity one or more of the antenna grid lines replace the side rear glass.
- If all circuits test normal, replace the radio.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Control Module References for radio replacement, setup, and programming. Programming and Relearning
- Radio Antenna Module Replacement (Utility)
- Fixed Antenna Replacement (Avalanche/Escalade EXT)
- Radio Antenna Cable Extension Cable Replacement (Avalanche/Escalade EXT)
- Digital Radio Antenna Cable Replacement
- Quarter Window Replacement. Verification Tests