Toyota Repair: OVERDRIVE SHIFT OF 1989 TOYOTA CAMR, ted ritter, toyota camry

Question
Dear Ted Ritter,
We are lucky that there's some people like you helping others.
Ted, the overdrive of my '89 Toyota Camry, Automatic Transmission, 4 cylinder was erratic. Sometimes it works, then it's not. specially coming from park or stopped position, I have to press the gas pedal hard to give power, then it jerk a little bit going to next gear.
When the O/D is working or when press the button OFF/ON, the transmission is good shape, it has power, NO PROBLEM.
Ted, I've changed the thermostat thinking that the ECU was not reading the right temperature, BUT IT'S STILL THE SAME RESULTS. Is this a solenoid problem inside the transmission?
IN YOUR EXPERTISE , WHAT'S THE CAUSE OF THIS ERRATIC FUNCTION OF THE OVERDRIVE?

Thank you very much, much appreciated.

Rey M.  

Answer
Even these early O/D systerms had some sort of onboard diagnostic capability though somewhat limited, if there was a solenoid malfunction the O/D light on the dash would either remain on all the time or flash so I don't think it's a control problem but rather a hydraulic problem which means the transmission is having some wear problems and may have some internal hydraulic pressure leakage, the bottom line is that the transmission will probably need replacement.