Radio - Interference or Static on AM Band
91chevy23
GMC NUMBER: 91-9A-153
GROUP: 9A Audio Systems
DATE: October, 1991
CORPORATE NUMBER: 161003
SUBJECT: AM RADIO INTERFERENCE OR STATIC (ADDITION OF RADIO GROUND KIT)
MODELS: 1985-1991 M/L VANS
Some 1985-91 M/L vans may experience ignition static, popping, and/or a whine noise on AM radio.
To repair this condition, it will be necessary to ground the engine cover to frame assembly, using an engine ground cover kit (P/N 15665468).
For 1989 and prior vehicles, the engine cover should be grounded using braided mesh ground strap (P/N 06287160) or equivalent and the rivet and washer provided in the service kit. A flat washer may be necessary to install the braided mesh ground strap to the cover. This washer is listed in the parts information below and is not a part of the service kit. The service kit has been incorporated into 1992 production vehicles.
If condition remains, it may also be necessary to ground the radio antenna at the coaxial connector.
Figure 1:
Figure 2:
SERVICE PROCEDURE:
1990-1991 Vehicles
1. Remove the engine cover from the vehicle.
2. Pull the carpet back from the cover so that the mounting bracket stud is exposed (figure 1).
3. Install the engine cover ground kit (P/N 15665468) to the engine cover (figure 2).
- Place the strap provided in the engine cover ground kit on the engine cover mounting bracket stud, while making sure that the U shaped side is facing upward. Mark the engine cover where the rivet should go (figures 1 and 2).
- Drill a 7/64-inch hole to accommodate the rivet provided in the kit.
- With the ground strap in place, position the rivet through the ground strap and the engine cover.
- Place the raised washer provided in the engine cover ground kit on the aluminum side of the engine cover, and center the washer over the rivet. Press the washer into the insulation with your thumb or equivalent, while making sure the raised side of the washer is facing the aluminum side of the engine cover.
Important
To achieve a good ground, the raised side of the washer provided in the service kit must face the aluminum.
4. Secure the ground strap to the engine cover by installing the pop rivet using a standard pop rivet tool or equivalent.
5. Verify that a good ground exists.
6. Install the engine cover to the vehicle.
Figure 3:
Figure 4:
1985-1989 Vehicles
1. Remove the lower instrument panel extension if equipped.
2. Pull the carpet back to expose the right hand cable mounting stud (figures 3 and 4).
3. Install a braided mesh ground strap or equivalent to the engine ground cover using the washer and rivet provided in the service kit. A 10-inch (254 mm) braided mesh ground strap (P/N 06287160) and a washer (P/N 15684753) will also be necessary for installation.
- Measure and make a mark four inches directly above the right cable mounting stud (figure 4).
- Drill a 7/64-inch hole to accommodate the rivet.
- Install the rivet through the washer (P/N 15684753), braided mesh ground strap (P/N 06287160) in that order, and through the engine cover.
- Place the raised washer provided in the service kit over the rivet, while making sure that the raised end is facing the aluminum.
Important
To achieve a good ground, the raised edge of the washer provided in the kit must face the aluminum.
4. Secure the braided mesh ground strap to the engine cover with a standard pop rivet tool or equivalent.
5. Place the engine cover on the vehicle (do not fasten).
6. Attach the free end of the braided mesh ground strap to the right hand cable mounting stud, install cable, and tighten nut.
7. Verify that a good ground exists.
8. Fasten the engine cover to the vehicle.
1985-1991 Vehicles If condition persists, ground the antenna at the coaxial cable.
1. Remove the RH instrument panel filler panel.
2. Locate the antenna coaxial connection and visually check the cable for corrosion/good connection at the mating area. Replace if necessary.
3. Wrap the antenna coaxial connector with aluminum tape. While taping, add a braided ground strap and allow one end to remain free. Take the free end and ground to a suitable chassis ground.
4. Verify that a good ground exists.
5. Install the instrument panel filler panel.
Note: Check the base of the antenna to verify that it is tight and free from corrosion. If corrosion exists, remove or replace the antenna as required. Check the base antenna screws to verify that they are metal. Plastic coated screws will not provide the necessary ground.
SERVICE PARTS INFORMATION
Part
Number Description
15665468 Engine Cover Ground Kit
(Ground Strap, Pop Rivet, Raised Washer)
06287160 Braided Mesh Ground Strap
(10 inches long)
15684753 Flat Washer
Parts are currently available from GMSPO.
WARRANTY INFORMATION For vehicles repaired under warranty use:
Labor Operation: T7346
Labor Time: 0.4 hrs.
Note: Labor Operation is coded to base vehicle coverage in the Warranty System.