For 1990-2009 cars

# Ignition Noise or Interference Heard Through the Radio Speakers

Subject: | Ignition Noise or Interference Heard Through the Radio Speakers -- Diagnose and Repair as Required -- This bulletin is being revised to add 1996 model year and new diagnostic procedures, and supersedes bulletin 95-T-28, which should be discarded.

Models: | 1995-1996 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:

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.

Audio Noise Diagnosis
Symptoms | Model Year | VIN Breakpoint | Possible Cause -- Refer to appropriate symptom steps in the Symptom Diagnostic Chart on the following page.
--- | --- | --- | ---
Ignition noise or interference heard through the radio speakers on both AM and FM radio stations that increase or decrease with engine RPM -- warm or cold engine. | 1995 | Vehicles built before and including VIN SZ324226 | 1,2,3,4,5
1995 | Vehicles built after and including VIN SZ324227 | 1,2,3,4
1996 | Vehicles built before and including VIN TZ242661 (L24) and VIN TZ241427 (LLO) | 1,3,4
Ignition noise or interference heard through the radio speakers on both AM and FM radio stations that increase or decrease with engine RPM -- cold engine only. | 1996 | Vehicles built up to and including VIN TZ309319 | 1,3,4,6

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

Symptom Diagnosis Chart
Symptom Step | Possible Causes | Possible Solutions
--- | --- | ---
1 | Generator Noise | Disconnect the generator connector and retest. If the noise is eliminated, refer to appropriate audio diagnostic chart for generator noise elimination in the Audio section of the 1995 Electrical Service Manual or the 1996 Audio System & I/P Cluster Service Manual.
2 | Electronic ignition (EI) module harness routing | Re-route the EI module harness to achieve at least 24.5 mm (1.0 in) clearance between the EI module wires and spark plug wires.
3 | Ignition wire terminal tightness, electronic ignition (EI) module terminal corrosion or damaged spark plugs Refer to Note 1 | Corrosion on the EI module posts, ignition wires not properly seated or damaged spark plugs. Refer to EI Module and Spark Plug Inspection Procedure in this bulletin.
4 | Antenna system ground | Repair the antenna system ground. Refer to Antenna System Ground Check in the Audio section of the 1995 Electrical Service Manual or the 1996 Audio System & I/P Cluster Service Manual.
5 | Radio without enhanced noise reduction circuitry Refer to Note 2 | Refer to Radio Enhanced Noise Reduction Circuitry Identification Procedure in this bulletin.
6 | Spark Plugs gapped at 0.060 in

• | L24 -- AC 41 -- 608

• | LLO -- AC 41 -- 607

Refer to Note 3

Replace the spark plugs with new spark plugs gapped at 0.040 in according to the Technical Information Bulletin 96-T-25, Engine Cranks but will not Start, or Engine Stalls Immediately After Start Followed by Extended Engine Cranking, and/or Ignition Misfire Resulting in DTCs P0300, P0301, P0302, P0303, P0304.

Refer to Table C under Parts Requirements in this bulletin for the correct part number.

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.

### EI Module and Spark Plug Inspection Procedure

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.

### Radio Enhanced Noise Reduction Circuitry Identification Procedure

From Symptom Diagnosis Chart Step 5

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

P/N | Description | Usage
--- | --- | ---
21023551 | Radio Asm -- AM/FM Stereo | UM7
21023552 | Radio Asm -- AM/FM Stereo & T/PLR | UM6
21023553 | Radio Asm -- AM/FM Stereo & T/PLR w/equalizer | UU6/UP6

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:

P/N | Radio S/N -- Original Equipment S/N | Description | Usage
--- | --- | --- | ---
21023479 21021170 | 0009001 and higher | Radio Asm -- AM/FM Stereo | UM7
21023480 21021171 | 0038101 and higher | Radio Asm -- AM/FM Stereo & T/PLR | UM6
21023341 | 1043386 and higher | Radio Asm -- AM/FM Stereo & T/PLR w/equalizer | UU6/UP6

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.

### Parts Requirements:

Table A -- Spark Plug Wires
P/N | Description | Usage | Model Year
--- | --- | --- | ---
21023738 | Wire -- Spark Plug No.1 Cylinder | LKO/L24 | 1995
21023739 | Wire -- Spark Plug No.2 Cylinder | LKO/L24 | 1995
21023740 | Wire -- Spark Plug No.3 Cylinder | LKO/L24 | 1995
21023741 | Wire -- Spark Plug No.4 Cylinder | LKO/L24 | 1995
21023742 | Wire -- Spark Plug No.1 Cylinder | LLO | 1995
21023743 | Wire -- Spark Plug No.2 Cylinder | LLO | 1995
21023744 | Wire -- Spark Plug No.3 Cylinder | LLO | 1995
21023745 | Wire -- Spark Plug No.4 Cylinder | LLO | 1995
21023727 | Wire -- Spark Plug No.1&4 Cylinders | L24 | 1996
21023728 | Wire -- Spark Plug No.2 Cylinder | L24 | 1996
21023729 | Wire -- Spark Plug No.3 Cylinder | L24 | 1996
21023730 | Wire -- Spark Plug No.1&4 Cylinders | LLO | 1996
21023731 | Wire -- Spark Plug No.2 Cylinder | LLO | 1996
21023732 | Wire -- Spark Plug No.3 Cylinder | LLO | 1996

Table B -- Radio Assemblies
P/N | Description | Usage | Model Year
--- | --- | --- | ---
21023551 | Radio Asm -- AM/FM Stereo | UM7 | 1995
21023552 | Radio Asm -- AM/FM Stereo & T/PLR | UM6 | 1995
21023553 | Radio Asm -- AM/FM Stereo & T/PLR w/equalizer | UU6/UP6 | 1995

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

Table C -- Spark Plugs/Vehicle Emissions Control Information Labels
P/N | Description | Usage | Model Year
--- | --- | --- | ---
21024004 | Spark Plugs AC 41 -- 628 0.040 in gap | L24 | 1996
21024005 | Spark Plugs AC 41 -- 627 0.040 in gap | LLO | 1996
Note: If spark plugs are replaced, the Vehicle Emissions Control Information Label must be replaced. Refer to Technical Information Bulletin 96-T-25, Engine Cranks but will not Start, or Engine Stalls Immediately After Start Followed by Extended Engine Cranking, and/or Ignition Misfire Resulting in DTC P0300, P0301, P0302, P0303, P0304.
Vehicle Emission Control Information Labels
21008376 | Federal Emission Control Information | L24 | 1996
21008377 | Federal Auto/Man Trans., California Auto Trans. Emissions | LLO | 1996
21008378 | California Emissions | L24 | 1996
21008379 | California Manual Transaxle Emissions | LLO | 1996
21008380 | Export | L24 | 1996
21008381 | Export | LLO | 1996

Table D -- Ignition Modules/Ignition Module Bolts
P/N | Description | Usage | Model Year
--- | --- | --- | ---
21021523 | Module Asm -- Elek Ign Cont | All | 1995
21022444 | Module Asm -- Elek Ign Cont | All | 1996
Note: Bolts must be replaced if ignition module is removed
Ignition Module Bolts
21021067 | Bolt/Screw -- Elek ICM -- Qty 4 | All | 1995
21023362 | Bolt/Screw -- Elek ICM -- Qty 4 | All | 1996

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.