QuestionWhile driving home highway at speed overdrive quite, like I pushed the button to off. All other gears shift normal. I took my 1990 4 cyl. auto truck to toyota dealer. Not fuses,not cylnoid, not sensor, power to trans. Took out trans replaced with used, no difference replaced original.. Could not fix. Took to trans shop, same story, but they took out trans checked out trans, replaced some gaskets,though may be no sealing, all looked good, no fillings good shape, re-installed no difference.Could not fix. Took to garage checked out same as others, replaced computer, no difference, still at last garage. Already spent way to much, help!!!!
AnswerIf the solenoid clicks when using the switch and the dash indicator light goes on/off then I can only think of one other thing it may be, there is an EFI temp sensor that sends a temp signal to the ECM, if it does not send the correct temp signal which shows that the engine has reached a certain temperature then overdrive will not occur, the wire may have come off or there is an open circuit or the sensor itself may need to be replaced, I think it's located near the thermostat, it has two wires on a connector, one wire is green/blue, the other is brown/black.
