Audio System - Ignition Noise Heard Through Speakers
BULLETIN NO.: 95-T-28AISSUE DATE: January, 1997
GROUP/SEQ. NO.: Electrical - 08
CORPORATION NO.: 589603R
SUBJECT:
Ignition Noise or Interference Heard Through Radio Speakers (Diagnose and Repair as Required)
This bulletin is being revised to add 1996 model year and new diagnostic procedures, and supercedes bulletin 95-T-28, which should be discarded.
MODELS AFFECTED:
1995 and 1996 Saturns
CONDITION:
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.
CAUSE:
Certain ignition components generate electrical signal noise that may enter the radio through the antenna system. This noise is called "frontway noise."
CORRECTION:
To verify possible ignition noise condition, perform the diagnosis under "Procedures" in this bulletin.
PROCEDURES:
IMPORTANT
After completing each procedure, check radio to see if condition has been eliminated before going to possible cause in chart.
To verify concern, refer to the diagnostic chart shown and verify that 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.
EI Module and Spark Plug Inspection Procedure
(From Symptom Diagnosis Chart, Step 3)
1. Remove spark plug wires from electronic ignition (EI) module and inspect for corrosion on spark plug wire boots and on the EI module tower terminals.
2. If corrosion is present:
^ Remove corrosion from EI module tower terminals using a Snap-on(R) 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 EI module tower terminals are damaged by corrosion (e.g. pitting), replace EI module. (Refer to "Table D" under "Parts Requirements" in this bulletin for correct part number for replacement spark plug wires.)
^ Replace corroded spark plug wire(s) with new service spark plug wires. Add a liberal amount of dielectric grease to the EI module tower 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 resistance of spark plug wires. Resistance should be 2.5k to 12k ohms. If spark plug wire(s) are out of specification, replace affected spark plug wire(s). When replacing spark plug wire, make sure to apply a liberal amount of dielectric grease inside spark plug wire boot.
4. If spark plug wires are within specification, visually check spark plugs for possible physical damage such as a cracked or broken insulator. If damage is evident, replace spark plug(s). If 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.
Radio Enhanced Noise Reduction Circuity Identification Procedure
(From Symptom Diagnosis Chart, Step 5)
Remove radio from vehicle and check radio part number. Refer to the table shown.
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 table shown.
If the serial number of the radio is higher than indicated in the above table, it already contains the enhanced noise reduction circuitry. Do not replace the radio. Return to the "Symptom 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 a replacement radio.
PARTS REQUIREMENTS
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).
DISCLAIMER