NO UPSHIFT AFTER DOWNSHIFT MODELS WITH 200C OR 200-4R

1984-86 PARISIENNE, BONNEVILLE, AND GRAND PRIX MODELS EQUIPPED WITH 200C OR 200-4R TRANSMISSIONS

"Please discard previous bulletin 86-7-14 due to additional service package information. "

A 1984 through 1986 THM 200-C or THM 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 should be installed. Refer to Figures 1, 2 and 3 for transmission nameplate information and to Figures 4, 5 and 6 for service parts identification. Chart A provides service package part numbers, transmission model applications and 1986 model start of production Julian dates for the THM 200-4R transmission and Chart B the same information for the THM 200C.

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 86-7-14 dated March, 1986.

CHART A - THM 200-4R

**1986 MODEL TRANSMISSION MODEL AND YEAR *SERVICE PACKAGE JULIAN --------------------------- PART NUMBER TRANSMISSION DATE ** 1986 1985 1984 --------------- ------------ ---- ---- ---- ---- 8639933 THM 200-4R 057 BRF BQ

8639934 THM 200-4R 336 HCF, KZF HG, OZ HG, OZ

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

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

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

***8639939 THM 200-4R N/A BQ CR

* Service Package contains (1) throttle valve plunger, (1) throttle valve plunger bushing, and (1) throttle lever and bracket assembly (NOTE: Throttle lever and bracket assembly part number 8648670 is available seperately)

** 1986 Model Julian date begins in calender year 1985

*** SERVICE PACKAGE 8639939 WILL NOT BE AVAILABLE UNTIL LATE SPRING 1986

CHART B - THM 200C MODELS

**1986 MODEL TRANSMISSION MODEL AND YEAR *SERVICE PACKAGE JULIAN --------------------------- PART NUMBER TRANSMISSION DATE ** 1986 1985 1984 --------------- ------------ ---- ---- ---- ----

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

8639932 THM 200C 062 CAB, CUB, CS, CO, OI KAB, KBB CV, C5 C6, OI

8639933 THM 200C 062 HLB HL, OU OU

8639940 THM 200C N/A JY CZ, JY

* Service Package contain (1) throttle valve plunger, and (1) throttle valve plunger bushing

** 1986 Model Julian date begins in calender 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.