Audio System AM Band Radio Noise

Customers may comment that while listening to certain AM radio stations, they hear ignition related noise. The radio noise follows engine RPM.

During normal engine operation, ignition components in the engine compartment emit certain electrical noise. Depending on the location of the vehicle antenna mast, these electrical noises may enter the radio through the antenna system. These noises may then be interpreted by the radio as radio signals and be amplified in the form of noise. Typically, the only AM radio stations that are affected are fringe stations. Fringe stations are stations that are beyond their intended usable range.

Important: The range for most AM stations is greater than for FM stations, especially at night. The longer range, however, can cause stations to pick up noise from things like ignition components, storms, and power lines.

Attach a ground strap from the upper engine mount to the right side strut attachment stud.

1. With the engine running, verify the noise is on fringe AM stations only. If the noise is on AM and FM, just FM, and/or cassette/CD, refer to the Audio System section of the appropriate model year Audio System & I/P Cluster service manual and/or Technical Bulletins 96-T-28A or 98-T-19.
2. Using a jumper wire with alligator clips, attach one end to the engine front cover torque axis mount stud and the other end to the strut tower nut, do not attach to the stud, the nut is a better ground.

•	If the noise is reduced or eliminated, continue with step 3.

•	If the noise is not reduced or eliminated, refer to the Audio System section of the appropriate model year Audio System & I/P Cluster service manual for additional diagnostic information.

Important: When removing the engine mount-to-front cover nut, use a 7 mm wrench on top of the stud to prevent the stud from rotating.




3. Remove the engine mount-to-front cover nut from the rear stud.

•	If the stud rotates while removing the nut, go to step 4.

•	If the stud does not rotate while removing the nut, go to step 7.

Notice: Do not over apply thread locker or allow it to accumulate in the bottom of the hole. The front cover could be damaged when the stud is installed.

Important: If reinstalling a previously installed stud, the threads must be thoroughly cleaned before applying Loctite 242™ P/N 21485277, or equivalent. If installing a new stud, the stud may or may not have a pre-applied threadlocker. The front cover hole must be thoroughly cleaned using a 10 mm x 1.5 mm tap to clean the treads and compressed air to remove particles from the stud hole.

4. Apply Locktite™ 242 P/N 21485277, or equivalent, to 6-8 middle treads of clean front cover stud.
5. Apply Locktite™ 242 P/N 21485277, or equivalent, to the treads of the holes in the engine front cover using a cotton tipped applicator keeping the top 2 treads clean.
6. Install the stud into the front cover.

Tighten
Tighten the stud to 25 N·m (18 lb ft).

7. Using the ground strap P/N 21012387, attach one end to the engine mount rear stud> Install a new nut P/N21006320.

Tighten
Tighten the nut to 50 N·m (37 lb ft).

Important: Use a new nut P/N21012387 to service all years, 1995-1999. The new nut has a lower profile which allows for additional free tread above the nut.

8. Using a new nut, p/n 21012387, attach the other end of the ground strap to the outboard side strut stud.

Tighten
Tighten the nut to 29 N·m (21 lb ft).

9. With the radio tuned to a fringe AM station and with the engine running, verify the noise is reduced or eliminated. If the noise is not reduced or eliminated, refer to the Audio System section of the appropriate model year Audio System & I/P Cluster service manual and/or Technical Service Bulletins 95-T-28A or 98-T-19.