SHUDDER OR VIBRATION AT LOW SPEEDS (INSTALL NEW PROM)

Subject: SHUDDER OR VIBRATION AT LOW SPEEDS (INSTALL NEW PROM)

Models Affected: 1990 - 1992 TRANS SPORT WITH 3.1L

This bulletin has been revised to include the 1992 model year. This bulletin cancels and replaces bulletin 91-6-47 issued 8191.

Condition:

---------- Some owners of 1990 - 1992 Trans Sport models with 3.IL (VIN D) engine may comment of a Shudder or Vibration at Low Speeds.

Cause:

------- This condition may be caused by the transmission converter clutch being engaged at 23 MPH.

Correction:

----------- If normal diagnostic procedures shown in your Service Manual (Section 6E2-B-3) do not correct this condition, a new PROM with a "TCC" (torque converter clutch) engagement speed of 35 MPH is available. The part numbers are as follows:

1990 Vehicles

Emission PROM Scanner Broadcast System Package No. I. D. Code ----------- ----------- ------- --------- California 16163425 3431 AYAC

Federal 16163426 3441 AYAD

1991 And 1992 Vehicles

Emission PROM Scanner Broadcast System Package No. I. D. Code ---------- --------- ------- ------ California 16164894 4911 AYHP

Federal 16164893 4901 AYHN

Note: This correction will have no impact on performance above 35 MPH.

Parts are currently available from GMSPO.

Labor Operation Number: T0500 Labor Time: .7 Hour

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.