SHIFT SPEED AND LINE PRESSURE CHARTS

Model and Year: 1991 B, F CARS AND M VAN WITH 4L60/700-R4 AUTOMATIC TRANSMISSION

This bulletin covers early introduction of 1991 HYDRA-MATIC 4L60 transmission models (Figure 1). Some 1991 vehicles scheduled for production in early 1990 will contain 1991 model year transmissions. This bulletin contains shift speed and line pressure charts for use in diagnosing these transmission models (Figures 2 and 3).

This information is not yet contained in any service manual. Please use these charts until the 1991 service manual is published.

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.