DRIVELINE VIBRATION OVER 37 MPH (REPLACE PROM). Buick Park Avenue 1994

REVISION: 06/05/97

THIS BULLETIN IS BEING REVISED TO INCLUDE VEHICLES WITH SUPERCHARGED (L67) ENGINES. PLEASE DISCARD CORPORATE BULLETIN #53-65-06 - (SECTION 6E - ENGINE FUEL & EMISSION). ______________________________________________________________________

SUBJECT: DRIVELINE VIBRATION OVER 37 MPH (REPLACE PROM)

MODELS: 1994-95 BUICK LESABRE, PARK AVENUE, ULTRA 1995 BUICK RIVIERA 1994-95 OLDSMOBILE EIGHTY EIGHT, NINETY EIGHT 1994-95 PONTIAC BONNEVILLE WITH 3.8L 3800 ENGINE (VINS L, K, 1 - RPOS L27, L36, L67)

CONDITION:

SOME OWNERS MAY COMMENT ON A CONDITION DESCRIBED AS A "VIBRATION", "MISS", "CHUGGLE", "HESITATION", OR "FISHBITE" SENSATION WHILE DRIVING THE VEHICLE AT 37 MPH OR HIGHER.

CAUSE:

WITH THE TORQUE CONVERTER CLUTCH (TCC) ENGAGED, ANY POWERTRAIN OR VEHICLE ROTATING DISTURBANCE IS TRANSMITTED TO THE PASSENGER COMPARTMENT.

IMPORTANT: VERIFY CONCERN WITH OWNER BEFORE PROCEEDING WITH CORRECTION.

CORRECTION:

DETERMINE THAT THE FOLLOWING CONDITIONS DO NOT EXIST BEFORE PROCEEDING:

1. OUT-OF-BALANCE TIRES 2. OUT-OF ROUND TIRES 3. ENGINE MISS DUE TO IGNITION RELATED COMPONENTS OR AN INOPERATIVE MECHANICAL FUNCTION 4. A/C COMPRESSOR CYCLING 5. TCC MALFUNCTIONS CAUSING EXCESSIVE SLIP VALUES AS MEASURED WITH A SCAN TOOL; OR 6. SPECIFIC ROAD CONDITIONS

IF IT IS DETERMINED THAT THE ABOVE CONDITIONS ARE NOT PRESENT AND NO OTHER CONDITIONS ARE CAUSING THE CONCERN AS OUTLINED IN SECTION 6E3-B IN THE APPROPRIATE SERVICE MANUAL, REPLACE PROM (REFER TO ATTACHED CHART). FOR SUPERCHARGED L67 ENGINES, CONTACT TECHNICAL ASSISTANCE. THIS PROM WILL ONLY RAISE THE THIRD GEAR TCC LOCK FROM 37 TO 50 MPH AND FOURTH GEAR TCC LOCK FROM 45 TO 54 MPH FOR VEHICLES EQUIPPED WITH VIN "L" AND "K" ONLY. REFER TO SECTION 6E3-C1 IN THE APPROPRIATE SERVICE MANUAL FOR PROM REPLACEMENT PROCEDURES.

IMPORTANT: NO OTHER DRIVEABILITY ISSUES ARE ADDRESSED WITH THIS PROM.

VERIFY THE CONCERN IS NO LONGER OCCURRING BEFORE RETURNING THE VEHICLE TO THE OWNER.

NOTE 1: ======

THE REVISED PROMS ARE NOT CONSIDERED A 100% CURE; HOWEVER, MOST OWNERS DO NOT PERCEIVE THE "CHUGGLE" OR "FISHBITE" SENSATION WITH THE HIGHER TCC LOCK UP SPEEDS.

NOTE 2: ======

THE REVISED PROMS MAY ADVERSELY AFFECT FUEL ECONOMY (USUALLY LESS THAN ONE MPG DEPENDING ON INDIVIDUAL DRIVING HABITS). BE SURE TO ADVISE THE VEHICLE OWNER OF THIS FACT.

IF UPON REPLACING THE PROM THE CONDITION IS STILL PRESENT, CONTACT TECHNICAL ASSISTANCE FOR FURTHER INSTRUCTION.

NOTE 3: ======

FOR SUPERCHARGED ENGINES, REVIEW CORPORATE BULLETIN NUMBER 77-65-15 AS ANOTHER POSSIBLE CAUSE OF CHUGGLE.

PARTS INFORMATION:

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION NUMBER: J6364 USE PUBLISHED LABOR OPERATION TIME.

FIGURES: 00 ATTACHMENTS: 01

Object Number: 86333 Size: FS

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.