DECEL STALL/CRANK ON START UP - NEW IAC MOTOR

SUBJECT: NEW IDLE AIR CONTROL (IAC) MOTOR FOR 3800 AND 3300 ENGINES

MODELS AFFECTED: 1988-90 ELECTRA/PARK AVENUE, RIVIERA/REATTA AND LESABRES EQUIPPED WITH 3800 (VIN C) ENGINE 1991 LESABRES EQUIPPED WITH 3800 (VIN C) ENGINE 1989-93 CENTURY AND SKYLARK MODELS EQUIPPED WITH 3300 (VIN N) ENGINE 1990-93 PARK AVENUE, LESABRE, RIVIERA/REATTA AND REGAL MODELS EQUIPPED WITH 3800 (VIN L) ENGINE 1991-93 PARK AVENUE/ULTRA MODELS EQUIPPED WITH 3800 S/C (VIN 1) ENGINE

Some of the models mentioned above may experience a decel stall or long crank on startup. This condition can sometimes be viewed on a scan tool as excessively high IAC counts at idle immediately after startup, or as a failure to return to the same (or similar) IAC counts displayed at idle after several throttle maneuvers.

If this condition is experienced and currently published service diagnostic procedures indicate a malfunctioning IAC motor, it will be necessary to install a new IAC motor.

It should be noted that two designs of IAC motors exist. The 3800 (VIN L) and the 3800 supercharger (VIN 1) use a triple slope design (see figure). The 3800 (VIN C) and 3300 (VIN N) use a dual slope design. The dual slope and the triple slope designs are not interchangeable. Several part numbers for IAC motors are being phased out to standardize usage and are being replaced by current production IAC motors. The chart below lists the application and appropriate service part numbers.

Parts are currently available from GMSPO.

ENGINE IAC SERVICE YEAR SERIES ENGINE/RPO VIN CODE PART NUMBER ---- ------ ---------- -------- -----------

1988-90 Electra/Park Ave/Ultra 3800/LN3 "C" 17112650 Riviera/Reatta and LeSabre

1991 LeSabre 3800/LN3 "C" 17112650

1989-93 Century and Skylark 3300/LG7 "N" 17112650

1990 Regal 3800/L27 "L" 17112649

1991 Park Ave/Ultra,Riviera/ 3800/L27 "L" 17112649 Reatta and Regal

1992-93 Park Avenue, LeSabre, 3800/L27 "L" 17112649 and Regals

1991-93 Park Ave/Ultra 3800 SC/L67 "1" 17112649

WARRANTY INFORMATION:

Use applicable Labor Operation and Time.

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.