NO 2-1 COASTDOWN SHIFT WHEN COLD-INSTALL NEW VALVE SPRING

TRANSMISSION APPLICATIONS: SUBJECT: ------------------------- ------- 1987-88 200-4R (MW9) NO 2-1 COASTDOWN SHIFT WHEN TRANSMISSION IS COLD AND AMBIENT TEMPERATURE IS FREEZING OR BELOW

TRANSMISSION MODELS: VEHICLE APPLICATIONS: ------------------- -------------------- CCF, CHF, CRF, CTF, B, G CARS CYF, CZF

BULLETIN COVERS: (Figure 1) --------------- Some of the subject vehicles with a THM 200-4R transmission may exhibit the following condition:

No 2-1 coastdown shift after being started up cold in cold weather (freezing or below) and driven a short distance and stopped. The car may start out in 2nd gear after this first stop, and then exhibit normal coastdown shifts thereafter. This condition will occur with the selector in D3 or D4 only and may be eliminated by installing a new 1-2 throttle valve spring (Figure 1, Item 335) in the valve body.

DATE OF PRODUCTION CHANGE: (Figure 2) ------------------------- January 12, 1988 (Julian Date 012) 1-2 throttle valve spring changed to eliminate 2nd gear starts as described above.

SERVICE ACTION:

Remove the valve body (on-car service procedure--the 1-2 accumulator housing will hold the spacer plate and check balls in place). Place the valve body on a clean workbench and change the 1-2 shift valve spring. Do not attempt to change the spring as an on-car service procedure.

SERVICE PARTS INFORMATION:

Part No. Description Years Models -------- ----------- ----- ------ 8634619 1-2 Throttle 1987-1988 CCF, CHF, CRF, Valve Spring CTF, CYF, CZF

SERVICE MANUAL REFERENCE:

Refer to the unit repair section of the THM 200-4R Service Manual for valve service procedures.

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.