For 1990-2009 cars

# 3-2 TIP-IN FLARE/SLIP BUMP AT SPEEDS OF 18-24 MPH

TRANSMISSION APPLICATIONS: 4T60 AND 2.8L OR 3.1L

#### TRANSMISSION MODELS:

#### SUBJECT: 3-2 TIP-IN FLARE/SLIP-BUMP AT 29- 38 KM (18-24 MPH)(INSTALL NEW PARTS)

VEHICLE APPLICATIONS: 1989-91 A,W CARS WITH 4T60 AND 2.8L (VIN W) OR 3.lL (VIN T)

#### BULLETIN COVERS:

Some 1989 through 1991 A or W-cars equipped with a 2.8L (VIN W) or 3.1L (VIN T) engine and a HYDRA-MATIC 4T60 transaxle may exhibit a 3-2 light throttle tip-in flare/slip-bump condition at 29-38 km (18-24 MPH). A new 3-2 line control system and spacer plate are now available that will better control the transaxle operation. These conditions can be corrected by replacing the components listed under "Service Procedure".

SERVICE PROCEDURE: Refer to Figure 1 ---------------------------------------- To repair a 3-2 light throttle tip-in flare/slip-bump condition at 18-24 mph, order and install the parts for the appropriate model listed under "SERVICE PARTS INFORMATION".

#### IMPORTANT: Do not interchange parts between the two different 3-2 line control systems located in the channel plate assembly or the following two misbuilds could occur:

1. All upshifts at the minimum shift speed (early) for any throttle position. This would be caused by the 3-2 line control valves {both primary (431) and secondary (436)} being used with the spacer plate assembly for the plug line control valve (430); the valves will not work correctly because there are no fluid passage holes in the spacer plate assembly designed to function with the plug valve.

2. All 2-3 upshifts at minimum shift speed (early) for any throttle position. This would be caused by using the 3-2 line control plug (430) with the new spacer plate assembly designed to function with the 3-2 line control valves {both primary (431) and secondary (436)}.

#### DATE OF PRODUCTION CHANGE:

The new 3-2 line control system and spacer plate were implemented into production starting December 13, 1990 (Julian Date 347).

#### SERVICE PARTS INFORMATION

#### IMPORTANT: If servicing a CHH, CJH, YKH or YLH model built before march 27, 1989 (Julian Date 086), order and install package 8662992 for CHH or YKH and 8662993 for CJH or YLH models. Do NOT use the valve body spacer plate assembly from these packages; use the appropriate spacer plate from the packages listed below, along with all the components included in the package.

Part numbers 8662992 and 8662993 are currently available from CANSPO.

Part Model Number Description Usage ------- ----------------------------------------------- ----- 8675992 Package, 3-2 Slip-Bump Kit CHH - Instruction Sheet YDH - Valve, 3-2 Line Control Valve Primary (431) YKH - Valve, 3-2 Line Control Valve Secondary (436) LMH - Retainer, 3-2 Line Control (435) YSH - Spring, 3-2 Line Control (432)

8675993 Package, 3-2 Slip-Bump Kit CJH - Instruction Sheet YHH - Valve, 3-2 Line Control Valve Primary (431) YLH - Valve, 3-2 Line Control Valve Secondary (436) LNH - Retainer, 3-2 Line Control (435) YTH - Spring, 3-2 Line Control (432)

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.