Bonneville V6-231 3.8L VIN 3 SFI (1988)
Technical Service Bulletin # 90729
Date: 900201
A/T - Delayed Upshifts When Cold or Hot
Bulletin Number:
90-7-29
Reference Number:
077106
Publish Date:
2/90
Subject:
INTERMITTENT DELAYED UPSHIFTS WHEN COLD OR HOT - TV PLUNGER/BUSHING ASSEMBLY NOW AVAILABLE
Models
Affected:
1985-90 6000, BONNEVILLE AND GRAND PRIX MODELS W/4T60
Bulletin Covers:
Background and diagnosis information on the throttle valve (T.V.) and governor system that control shift timing and not shift feel. The T.V.
plunger/bushing assemblies will now be available for service. Before the T.V. plunger/bushing assembly is replaced, the entire T.V. system must be
checked. The T.V. SYSTEM may cause one or more of the following conditions:
-
Delayed upshifts (may also be caused by sediment between the governor seat and ball(s)).
-
Early upshifts (may also be caused by the governor weight(s) binding on the governor rotor). The rotor is not indexed correctly.
-
No upshifts (may also be caused by sediment between the governor seat and balls).
-
1-2 shift at full throttle only.
-
No full throttle or part throttle detent downshifts.
-
Intermittent second gear starts.
-
Harsh 3-2 downshifts.
Figure 1 - T.V. Plunger/Bushing And Throttle Valve
IMPORTANT:
Some of the conditions listed above could be intermittent or all the time. The T.V. valve and bushing (308 and 309) may be worn, allowing sediment to
cause the plunger to stick in the bore intermittently. Another concern could be the throttle valve (311) being stuck down in the bore. Sediment could be
the cause of both of these concerns.
Either of these conditions could cause delayed upshifts when the transaxle is cold or hot. (Figure 1)
The listed conditions may be caused by a T.V. cable that is:
-
Improperly set
-
Kinked or binding
-
Disconnected
-
Broken
-
Wrong part
Diagnosis and Service Procedure
