Ignition Noise or Interference Heard Through the Radio Speakers

On some vehicles, the customer may comment that noise or interference can be heard through all radio speakers on both AM or FM radio stations.

Certain ignition components generate electrical signal noise that may enter the radio through the antenna system. This noise is called frontway noise.

To verify possible ignition noise condition, perform the diagnosis under Procedures in this bulletin.

To verify the concern, refer to the following diagnostic chart and verify that the concern is related to ignition noise.

Important: The noise reduction circuitry enhancement was implemented for the reduction of ignition noise only. It is not designed to reduce or eliminate other types of audio noise.

Important: After completing each procedure, check the radio to see if the condition has been eliminated before going to the possible cause chart.

Note 1: Vehicles built after TZ242661 (L24) and TZ241427 (LLO) have the new spark plug wires with stainless steel clips on the EI module end.

Note 2: A new radio, with a radio circuitry enhancement is available for the reduction of ignition noise only for vehicles built before and including VIN SZ324226. For vehicles built after and including VIN SZ324227 and all 1996 vehicles, the new radios with radio circuitry enhancement have been installed in production.

Note 3: Vehicles built after TZ309319 have 0.040 in gapped spark plugs installed during production.

From Symptom Diagnosis Chart Step 3

1. Remove the spark plug wires from the electronic ignition (EI) module and inspect for corrosion on the spark plug wire boots and on the EI module tower terminals.
2. If corrosion is present:

•

Remove the corrosion from the EI module tower terminals using a Snap-on® bronze wire brush (MB5B) or equivalent. Do not use any solvents or cleaners to aid in removal. Also, do not use power equipment to drive the cleaning brush. If the EI module tower terminals are damaged by corrosion (e.g. pitting), replace the EI module. Refer to Table D under Parts Requirements in this bulletin for the correct part number for replacement spark plug wires.

•

Replace corroded spark plug wires with new service spark plug wires. Add a liberal amount of dielectric grease to the EI module lower terminals before installing the new spark plug wires. Refer to Table A under Parts Requirements in this bulletin for correct part number for replacement spark plug wires.

•	Verify Repair, if symptoms are still present, return to the Symptom Diagnosis Chart in this bulletin.

3. If no corrosion is present, check the resistance of the spark plug wires. Resistance should be 2.5k-12k ohms. If the spark plug wires are out of specification, replace the affected spark plug wires. When replacing spark plug wire, make sure to apply a liberal amount of dielectric grease inside the spark plug wire boot.
4. If the spark plug wires are within specification, visually check the spark plugs for possible physical damage such as a cracked or broken insulator. If damage is evident, replace the spark plugs. If the vehicle is a 1996 vehicle built up to and including VIN TZ309319, refer to Symptom Step 6 in Symptom Diagnosis chart before replacing any damaged spark plugs.

From Symptom Diagnosis Chart Step 5

Remove the radio from the vehicle and check the radio part number. Refer to the following table:

If the radio P/N is listed above, it contains the enhanced noise reduction circuitry. Do not replace the radio. Return to the Symptom Diagnosis Chart.

If the radio P/N is not listed above, determine the serial number of the unit and refer to the following table:

If the serial number of the radio is higher than indicated in the above table, it already contains enhanced noise reduction circuitry. Do not replace the radio. Return to the Symptoms Diagnosis Chart.

If the serial number of the radio is less than what is shown in the above table, refer to Table B of Parts Requirements in this bulletin for the correct part number of the replacement radio.

Important: The three re-manufactured radios listed above have the noise reduction circuitry installed regardless of radio serial number.

Claim Information: To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System using the appropriate Electronic Labor Time Guide and Labor Operation Code R0760 -- Replace Radio Receiver or J4227 -- Replace All Spark Plugs.