Questioni was merging onto the freeway yesterday, and did a hard acceleration, for about three seconds. since than the car has not given me fourth or overdrive at all. i've tried turning overdrive off, releasing the gas pedal at proper shift points, etc. i also do not have the check engine light on. will a code reader even help in this instance? any idea what it could be?
AnswerHi, Tom. It's possible you may have a trouble code even though there is no check engine lamp, so there remains the possibility that the code reader will help you.
First, however, start your car and toggle the overdrive switch. Does the "O/D OFF" lamp illuminate and turn back out? If not, it's almost a certainty the overdrive switch is the culprit. If not, I'd say the switch is still the first thing to check, but you'll need to remove the console and check the output from the switch. Basically, the switch works by sending 12V to either the transmission control module (TCM) for overdrive on, or the lamp in the cluster for overdrive off. Typically, the TCM has no way to determine if the switch is working properly, so the check engine lamp will never come on if the switch is the problem.
