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Old 05-04-2003, 11:35 AM
psfred psfred is offline
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Adam:

All three things regulate what is know as the "control pressure" in the hydraulic circuit in the transmission. Shifting is accomplished by moving spool valves to open or close openings in order to direct hydraulic fluid to the apporpriate clutches.

What is happening to you is that either the control pressure is signalling fast upshift or a valve is stuck.

The kickdown solenoid causes a pressure change (I don't know if it is up or down) in control circuit to delay upshifts and to downshift the transmission if already in 3rd. Upshift will still occur, but at a higher speed.

The governor is a speed sensing device, either a spring loaded centrifugal valve that allows more pressure into the control circuit the faster the output shaft goes, or a shaft driven pump that does the same thing.

The control rod operates another variable valve in the same circuit to vary the control pressure relative to throttle opening.

One or more of these is not working properly, or there is a problem in the valve body (such as a stuck spool valve or a broken spring).

All I would do would be to verify the operation of the control rod, the vacuum line to the modulator and modulator (should only control shift quality, and it will be VERY hard if something is leaking) and the operation of the kickdown solenoid. A fluid and filter change will verify that you don't have a clogged filter and resultant low pressure.

If none of this fixes the problem, time to go to the mechanic.

Peter
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