A/T - No Upshift Condition After Downshift
Number 86-7-14A Date 5/86Subject: NO UPSHIFT CONDITION AFTER DOWNSHIFT
1984-86 PARISIENNE, BONNEVILLE, AND GRAND PRIX MODELS EQUIPPED WITH 200C OR 200-4R TRANSMISSIONS
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:
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.