NO UPSHIFT AFTER A PART OR FULL THROTTLE DETENT

MODELS AFFECTED: 1984-1986 THM 200C, 200-4R TRANSMISSIONS

NOTE: This bulletin supersedes bulletin 86-7200-2 dated, March, 1986.

A 1984 through 1986 THM 200C or 200-4R transmission may exhibit a no upshift condition after a part or full throttle downshift.

This condition may be caused by internal leakage hydraulically locking the throttle valve plunger. If this occurs, the line pressure remains at a boosted level, resulting in a no upshift condition.

To repair this condition, a new throttle valve plunger and throttle valve bushing, and for some models, a throttle valve lever and bracket assembly should be installed. Refer to Figures 1 and 2 for transmission nameplate identification information and to Figure 3 and 4 for service parts identification. The chart provided indicates service package part numbers, and transmission model applications and 1986 model start of production Julian dates for the THM 200C and 200-4R transmissions.

IMPORTANT: The highlighted transmission models and service package part numbers identify those packages which include the throttle lever and bracket assembly. These service packages were not included in the original bulletin.

**1986 Transmission Model and Year *Service Model Package Transmission Julian **1986 1985 1984 Part No. Date -------- ------------- ---- ------ ---- ----

8639931 THM 200C 291 BHB,HHB BH,HH,OR BH,OR

8639932 THM 200C 062 CAB,CUB CS,CO,CV 01 KAB,KBB

8639933 THM 200C & 062 HLB HL,OU OU THM 200-4R 057 BRF BQ

8639940 THM 200C N/A JY CZ,JY

8633934 THM 200-4R 336 HCF,KZF HG,OZ HZ,OZ

8639935 THM 200-4R 057 CAF,CHF CH,CQ,CR CQ,OM CRF,CZF CY,OM

8639936 THM 200-4R 336 HFF,KBG HE,OG,OJ HE,OG,OJ KCF,KJF

8639937 THM 200-4R 336 AAF,ABF AA,AP,AO AA,AP,BT APF BY,CH

8639939 THM 200-4R N/A BQ CR

* The highlighted service packages contain:

(1) Throttle valve plunger (1) Throttle valve plunger bushing, and (1) Throttle lever and bracket assembly

All other service packages contain:

(1) Throttle Valve plunger, and (1) Throttle Valve plunger bushing.

(Note: Throttle lever and bracket assembly part number 8648670)

** 1986 Model julian date begins in calendar year 1985.

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.