HARSH ENGAGEMENT CONDITIONS SYMPTOMS/DIAGNOSIS/REPAIRS

TRANSMISSION APPLICATIONS: SUBJECT: ------------------------- ------- 1987-1988 THM 440-T4 (ME9) HARSH ENGAGEMENT CONDITIONS: I. PARK OR NEUTRAL TO DRIVE OR REVERSE II. REVERSE TO DRIVE - VEHICLES WITH 2.8L ENGINES ONLY

TRANSMISSION MODELS: VEHICLE APPLICATIONS: ------------------- -------------------- ALL MODELS A, C, H, E, K, W CARS

BULLETIN COVERS:

Harsh engagement conditions and specific service information for 1987 and 1988 cars equipped with a THM 440-T4 transaxle. Other items which cause harsh engagement conditions are:

- vacuum leaks (low vacuum supply to the vacuum modulator) 33-46 Cm Hg (13-18 In Hg) required

- stuck modulator valve - missing #9 checkball

DATE OF PRODUCTION CHANGE: (Figure 1) -------------------------- November 24, 1987 (Julian Date 328), all THM 440-T4 transaxles were built using a new 1-2 servo cushion spring, reverse servo cushion spring and reverse servo return spring.

SERVICE ACTION: (Figure 2) --------------- I. Harsh Engagement From Park Or Neutral To Drive Or Reverse - 1987-1988 A, C, H, E, K Cars Without 2.8L Engines

1. Remove the 1-2 servo assembly and the reverse servo assembly from the transaxle.

2. Disassemble and replace the 1-2 servo cushion spring (559) and the reverse servo cushion spring (549) with the correct part listed in the Service Parts Information section.

3. Install the 1-2 servo assembly and reverse servo assembly in the transaxle.

II. Harsh Engagement From Reverse To Drive, Park Or Neutral To Drive Or Reverse - 1987-1988 A Cars With 2.8L Engines Only 1988 W Cars With 2.8L Engines Only

1. Remove the 1-2 servo assembly and the reverse servo assembly from the transaxle.

2. Disassemble and replace the 1-2 servo cushion spring (559), the reverse servo cushion spring (549) and the reverse servo return spring (552) with the parts listed in the Service Parts Information section.

3. Install the 1-2 servo assembly and reverse servo assembly in the transaxle.

SERVICE PARTS INFORMATION:

Part No. Description Usage ------- ----------- ----- 8668121 Reverse Servo Cushion Spring (549) All 1987-88 Models

8668123 1-2 Servo Cushion Spring (559) All 1987-88 Models

8668127 Reverse Servo Return Spring (552) 1987-88 Vehicles w/ 2.8L Engines Only

SERVICE MANUAL REFERENCE:

Refer to the THM 440-T4 (ME9) Automatic Transaxle On Car Service section for appropriate service information.

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.