Mast Antennas

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Unplug antenna lead-in connector from radio receiver and plug a test antenna into radio. Make sure antenna base is grounded to the vehicle chassis and keep hands off the mast.

Check radio reception in an area away from electrical interferences. Tune to several weak and strong AM and FM stations. If the radio reception improved, the problem exists with the antenna and/Or lead-in cable. If the reception is still poor, refer to Audio System Troubleshooting Hints .

IMPORTANT: Always zero out the DMM before taking a resistance measurement in order to ensure an accurate reading.

Fig 1: Mast Antenna System

Courtesy of GENERAL MOTORS CORP.

Fig 2: Resistance Specification

Courtesy of GENERAL MOTORS CORP.

Refer to the table when testing the antenna and/Or lead-in cable.

Measure the resistance from the coax center conductor to antenna mast.
Total resistance from end to end of center conductor:
- RG-58/RG-59 type cable-less than 0.20 Ω
- RG-62/RG-62M type cable-less than 3.5 Ω
When checking the resistance, cautiously wiggle the lead-in tip and cable. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .
Measure the resistance from the cable center conductor to metal case.
Replace the antenna and/Or lead-in cable when the above readings are not obtained.

Some vehicles come equipped with a pre-amplified AM/FM antenna that is powered by SW 12+. If the antenna loses this power source or a ground, poor reception can occur. To see if your vehicle is equipped with a pre-amplified antenna refer to Radio/Audio System Schematics (UQ3/UQ5) or Radio/Audio System Schematics (UQ7 W/O Y91) or Radio/Audio System Schematics (UQ7 W/Y91) .