INFO. ON COIL & IGNITION HOUSING CHARACTERISTIC

SUBJECT: INFORMATION ON COIL AND IGNITION HOUSING CHARACTERISTIC CONDITIONS

MODELS: 1995-97 CHEVROLET CAVALIER 1997 CHEVROLET MALIBU 1988-93 CHEVROLET BERETTA 1988-97 PONTIAC GRAND AM 1995-97 PONTIAC SUNFIRE 1990-91 PONTIAC GRAND PRIX 1988-97 BUICK SKYLARK 1992-97 OLDSMOBILE ACHIEVA 1997 OLDSMOBILE CUTLASS 1987-91 OLDSMOBILE CALAIS 1990-91 OLDSMOBILE CUTLASS SUPREME WITH QUAD 4 AND LD9 TWIN CAM ENGINES (VINS A, D, 3, T - RPOS LG0, LD2, L40, LD9)

A HIGH PERCENTAGE OF IGNITION COILS AND IGNITION COIL HOUSINGS FROM THE ABOVE VEHICLES RETURNED UNDER THE CORPORATE WARRANTY RETURN PROGRAM HAVE BEEN TESTED WITH NO TROUBLE FOUND. A REVIEW OF WARRANTY REPAIR ORDERS HAS INDICATED THAT IGNITION COILS AND HOUSINGS ARE BEING REPLACED FOR CONDITIONS THAT ARE CHARACTERISTIC OF THIS IGNITION SYSTEM, AND NOT INDICATIVE OF A PART FAILURE.

A LARGE NUMBER OF IGNITION COIL HOUSINGS FROM 1995 AND 1996 QUAD 4 AND TWIN CAM ENGINES HAVE, AFTER A PERIOD OF USE, A CHARACTERISTIC MARKING OFTEN REFERRED TO ON REPAIR ORDERS AS "TRACKING". THIS "TRACKING" IS A CHARACTERISTIC OF THE HIGH VOLTAGE DISTRIBUTION THROUGH THE COIL HOUSING AND CAN EASILY BE WIPED AWAY WITH A DAMP RAG. THESE FALSE "TRACKS" ARE MOST OFTEN SEEN ON THE BOTTOM OF THE HOUSING BETWEEN THE SECONDARY IGNITION TERMINALS. (SEE FIGURE -1-) ACTUAL "TRACKING" FROM A HIGH VOLTAGE ARC, IS CHARACTERIZED BY DAMAGE TO THE COIL HOUSING WITH BLACK RESIDUE OR CARBON IMBEDDED IN HOUSING MATERIAL. THIS TYPE OF DAMAGE CANNOT BE WIPED AWAY TO ANY SIGNIFICANT DEGREE AND CAN OFTEN BE FELT AS WELL AS SEEN.

THERE HAVE ALSO BEEN NUMEROUS IGNITION COILS REPLACED DUE TO A CONDITION OFTEN DESCRIBED ON REPAIR ORDERS AS A "BURN" OR "BURNED". ALL QUAD 4 AND TWIN CAM IGNITION COILS HAVE A PAIR OF WELDS ON THE METAL PORTION NEAREST THE CONNECTION FOR THE PRIMARY WIRING. THESE WELDS ARE MADE AFTER THE COIL IS ASSEMBLED AND IN SOME CASES THE WELDING PROCESS LEAVES A BLACK MARK OR SOME DEBRIS ON THE COIL. THIS DEBRIS CAN BE WIPED AWAY WITH A DAMP RAG LEAVING BEHIND A SMALL BLACK MARK ON THE CORNER OF THE COIL NEAREST THE WELD. THIS WELD PROCESS IN NO WAY DEGRADES THE FUNCTION OF THE COIL AND IS A NATURAL PART OF THE MANUFACTURING PROCESS. (SEE FIGURE -2-)

IGNITION PARTS SHOULD BE DIAGNOSED BY USING THE INFORMATION CONTAINED IN SECTION 6E (DRIVEABILITY AND EMISSIONS OR ENGINE CONTROLS) OF THE APPROPRIATE SERVICE MANUAL, KEEPING THESE CHARACTERISTIC CONDITIONS IN MIND. ALWAYS FOLLOW THE STRATEGY BASED DIAGNOSTIC METHOD FOR IGNITION COMPONENTS, USING APPROPRIATE RESISTANCE VALUES AND INFORMED VISUAL INSPECTION IF NECESSARY.

FIGURE -1 LEGEND: 1. AREAS THAT MAY EXHIBIT FALSE "TRACKING".

FIGURE -2 LEGEND: 1. COIL WELD AREAS. 2. AREAS WHERE RESIDUE FROM WELDING AND CHARACTERISTIC DISCOLORATION MAY OCCUR.

FIGURES: 2 ATTACHMENTS: 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.

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