A/T - No Upshift Condition After Downshift
SUBJECT NO UPSHIFT CONDITION AFTER DOWNSHIFT NUMBER: 86-T-21A1984-86 CUTLASS SUPREME, DELTA 88, DATE: April 22,1986
NINETY-EIGHT WITH 200C or 200-4R
MODELS/YEARS TRANSMISSIONS AND 1984-85 TORONADO
SECTION: 7A
WITH 325-4L TRANSMISSIONS
This bulletin supercedes 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.
FIGURE 1 - THM 200-4R TRANSMISSION NAMEPLATE:
FIGURE 2 - THM 325-4L TRANSMISSION NAMEPLATE:
FIGURE 3 - THM 200C TRANSMISSION NAMEPLATE:
FIGURE 4 - TYPICAL 200C CONTROL VALVE ASSEMBLY:
FIGURE 5 - TYPICAL 200-4R CONTROL VALVE ASSEMBLY:
FIGURE 6 - TYPICAL 325-4L CONTROL VALVE ASSEMBLY:
CHART A - THM 200-4R AND 325-4L MODELS:
CHART B - THM 200C MODELS:
To repair this condition, a new throttle valve plunger, throttle valve bushing, and for some models, a throttle valve lever 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.
* 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
*All service packages contain (1) throttle valve plunger and (1) throttle valve plunger bushing
** 1986 Model Julian date begins in calender year 1985