IGN. NOISE AUDIBLE OVER BOSE RADIO SPEAKERS (REPLACE AMP.). Cadillac Eldorado 1993

====================================================================== REVISION 10/11/93

THIS BULLETIN IS BEING REVISED TO CHANGE THE CAUSE AND TO ADD A SECOND REPAIR PROCEDURE. PLEASE DISCARD PREVIOUS PUBLICATIONS: CADILLAC - T-93-61 AND GM OF CANADA 93-9-115. ======================================================================

SUBJECT: IGNITION NOISE AUDIBLE OVER BOSE RADIO SPEAKERS (REPLACE AMPLIFIER OR EXCHANGE RADIO RECEIVER)

MODELS: 1993 CADILLAC ELDORADO 1993 CADILLAC SEVILLE

SOME 1993 ELDORADOS AND SEVILLES EQUIPPED WITH BOTH THE NORTHSTAR POWERTRAIN (L37 OR LD8) AND THE BOSE RADIO (U1G) OPTIONS MAY EXPERIENCE A NOISE CONDITION OVER THE RADIO SPEAKERS THAT MAY BE DESCRIBED AS A "TICKING", "CRACKLING", "BUZZING", OR "STATIC" NOISE THAT USUALLY OCCURS AT ENGINE IDLE AND AT LOW VOLUME SETTINGS. THE NOISE IS PRIMARILY HEARD OVER THE FRONT SPEAKERS AND WILL OCCUR IN ALL AUDIO MODES: AM, FM, CD, AND TAPE. THE NOISE CONDITION MAY NOT BE PRESENT AT ENGINE SPEED GREATER THAN 1500 RPM.

THIS CONDITION MAY BE CAUSED BY THE ELECTRICAL NOISE GENERATED BY THE IGNITION SYSTEM THAT IS DETECTED BY THE BOSE AMPLIFIERS AND THE RADIO RECEIVER. NEW AMPLIFIERS (IN PRODUCTION SINCE BREAKPOINTS 607486 AND 813446 FOR ELDORADO AND SEVILLE, RESPECTIVELY) AND RECEIVERS ARE AVAILABLE TO CORRECT THIS CONDITION.

TO DETERMINE IF THIS BULLETIN APPLIES TO YOUR APPLICATION, USE THE FOLLOWING DIAGNOSIS PROCEDURE:

1. TURN ALL ACCESSORIES TO THE "OFF" POSITION. WITH THE KEY "ON" AND ENGINE "OFF", TURN THE RADIO TO THE MINIMUM VOLUME SETTING.

2. IF THE NOISE IS HEARD, THEN THIS BULLETIN DOES NOT APPLY TO YOUR APPLICATION. REFER TO SECTION 9A OF THE 1993 ELDORADO AND SEVILLE SERVICE INFORMATION MANUAL FOR DIAGNOSIS.

3. START ENGINE.

4. IF THE NOISE IS HEARD, THEN THIS BULLETIN DOES APPLY TO YOUR APPLICATION. DETERMINE WHICH SPEAKERS EXHIBIT THE CONDITION.

TO REPAIR THE CONDITION FOLLOW THIS PROCEDURE:

1. FOR VEHICLES BUILT AFTER BREAKPOINTS 607486 AND 813446, SKIP TO STEP 2. THIS IS THE BREAKPOINT FOR PUTTING THE REVISED AMPLIFIERS INTO PRODUCTION. FOR VEHICLES BUILT BEFORE THIS BREAKPOINT, REPLACE THE AMPLIFIERS OF THE SPEAKER PAIR THAT EXHIBITS THE NOISE. THE SPEAKER AMPLIFIERS OF THE SPEAKERS MUST BE REPLACED IN PAIRS (BOTH FRONTS OR BOTH REARS). FOR EXAMPLE; IF THE RIGHT FRONT SPEAKER EXHIBITS THE CONDITION, THEN BOTH THE LEFT AND RIGHT FRONT SPEAKER AMPLIFIERS MUST BE REPLACED. REFER TO THE 1993 ELDORADO AND SEVILLE SERVICE INFORMATION MANUAL, SECTION 9A, FOR THE REPLACEMENT PROCEDURE. THE AMPLIFIER PART NUMBERS ARE:

FRONT REAR

SEVILLE: 16193505 16193506 ELDORADO: 16193503 16193504

2. EXCHANGE THE RADIO RECEIVER, REQUESTING A RECEIVER WITH REVISION LEVEL E OR HIGHER, PER DELCO TECHNICAL DOCUMENT NUMBER RD93TBA09.

PARTS WILL BE AVAILABLE FROM GMSPO ON OCTOBER 18, 1993.

FIGURES: 0

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.