IGNITION NOISE IN RADIO SYSTEM REPAIR ANTENNA LEAD-IN GROUND

Model and Year: 1988-89 L CAR

CONDITION:

---------- Ignition noise is heard on AM and/or FM when the engine is running. When the ignition key is in the accessory (ACC) position the noise is gone.

CAUSE:

----- Poor antenna ground allows electrical signals from ECM into radio.

- The antenna lead-in connection located near the ECM may be loose or corroded. - The ground connection at the base of the mast antenna may not be clean or tight enough to ensure a good ground.

CORRECTION:

---------- Verify that an improper antenna ground is causing the noise by unplugging antenna lead-in at back of radio and plugging in a test antenna. Make sure test antenna base is grounded to the car chassis and keep hands off of the antenna. Check radio reception in an area away from electrical interference. These include tall buildings, metal structures, power lines, fluorescent lighting, and power tools.

If noise is present with test antenna, the noise is not coming through the antenna system. Check the Service Manual for steps to take to eliminate power line noise.

If reception is okay with the test antenna, the following steps should be taken to remove the noise from the existing antenna system:

- Tighten and clean antenna lead-in connection near ECM. Bend male connector tabs outward slightly, if needed.

- Route antenna lead-in as far away from the ECM as possible.

- Tighten and clean the ground connection at the base of the mast antenna.

- If the above steps do not eliminate the noise, wrap the lead-in cable near the ECM with aluminum tape and ground it to the body.

Use applicable labor operations and times.

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