QuestionI have a 1992 Toyota Paseo, which seems to be a great car. There is one problem. The transmission will kick itself out of overdrive, for no necessary reason, and stay out of overdrive for about 50 seconds, causing the engine to do 65 at 4100 RPM. Then after about 50 seconds, it kicks back into the 4th overdrive gear, and everything is fine. This happens one to two times on my 50 mile commute. It's a mildly hilly area, but nothing that should make it just do this, and it's done it on totally flat ground, and it's not from me depressing the accelerator, this just happens, and I let off the accellerator, and try to get it to kick back into the overdrive, and it does not, until it is ready to. I am just wondering what is causing this, I've checked the fluid level in the transmission, and it is seemingly OK (it's not too easy to get a good reading). Is there a such thing as maybe an overdrive relay, that could be bad? Also, if you do know what this is, how long can I operate the vehicle before this needs to be fixed. I am assuming that when it happens 4-5 times on my commute is when I need to get it attended to.
AnswerIt has an overdrive solenoid and an ECU temp sender, it's possible that one or the other may be malfunctioning.
The actual shift points for all the gears are determined by the computer based on sensor inputs, the temp sensor will not engage overdrive until the engine is warmed up, so a malfundtioning temp sensor could cause this problem, a malfunctioning solenoid could also be the problem, worst case it could be a loss of internal hydraulic pressure in the transmission because of an internal fluid leak or a bad ECU.
