For 1990-2009 cars

# NO UPSHIFT AFTER A PART OR FULL THROTTLE DETENT

#### MODELS/YEARS: 1984-86 CUTLASS SUPREME, DELTA 88, NINETY-EIGHT WITH 200C or 200-4R TRANSMISSIONS AND 1984-85 TORONADO WITH 325-4L TRANSMISSIONS

This bulletin supersedes Dealer Technical Bulletin 86-T-21 dated March 3,1986.

A 1984 through 1986 THM 200C, THM 200-4R or 1984-1985 THM 325-4L 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, throttle valve bushing, and for some models, a throttle valve lover and bracket assembly should be installed. Refer to Figures 1, 2, and 3 for transmission nameplate identification 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 2004R and 325-4L transmissions and Chart B provides the same information for the THM 200C.

Chart A - THM 200-4R and 325-4L Models

**1986 * Service Model Transmission Model and Year 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,0Z

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

THM 325-4L N/A AL,OK AL,OK

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

THM 325-4L N/A OE,OQ OE,OQ

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

THM 325-4L N/A AB,AE,AJ AE,AJ,BE

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

* Service package contains (1) throttle valve plunger, (1) throttle valve plunger bushing, and 91) throttle elver 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 200 C MODELS

**1986 * Service Model Transmission Model and Year Package Julian Part Number Transmission Date **1986 1985 1984 ----------- ------------ ----- ------ ----- ----

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

8639932 THM K200C 062 CAB,CUB CS,CO,CV OI KAB,KBB C5,C6,OI

8639933 THM 200C 062 HLB HL,OU OU

8639940 THM 200C N/A JY CZ,JY

* All service packages contain (1) throttle valve plunger and (1) throttle vlave plunger bushing

** 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.