DECELL STALL/CRANK ON START UP - NEW IAC MOTOR

Subject: DECEL STALL/CRANK ON STARTUP NEW IAC MOTOR

Models ALL 1988-1993 3800 AND 1992-93 Affected: 3300 ENGINES 1988-93 BONNEVILLE, GRAND AM AND TRANS SPORT MODELS

1988-91 BONNEVILLE VEHICLES EQUIPPED WITH 3800 (VIN C) ENGINE 1992-93 GRAND AM VEHICLES EQUIPPED WITH 3300 (VIN N) ENGINE 1990-93 BONNEVILLE VEHICLES EQUIPPED WITH 3800 (VIN L) ENGINE 1992-93 TRANS SPORT VEHICLES EQUIPPED WITH 3800 (VIN L) ENGINE 1992-93 BONNEVILLE VEHICLES 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 ---- ------ ---------- -------- ------------

1988-91 BONNEVILLE BODY 3800/LN3 "C" 17112650

1992-93 GRAND AM BODY 3300/LG7 "N" 17112650

1992-93 BONNEVILLE AND TRANS SPORT BODY 3800/L27 "L" 17112649

1992-93 BONNEVILLE BODY 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.