My great aunt gave me a 88 2wd pu with auth trans and I put a new radiator,hoses,belts,and thermostat but it wont shift into overdrive.Any suggestions on why its not shifting?Thanks

 

Is the engine coming up to normal operating temp (usually slightly below the half point of the gauge)?

Otherwise, it's probably a bad solenoid.

 

Overdrive off light on? Press the O/D button and what happens?

 

man i junked my 88 2wd A43D trans truck last april it always worked great hmm
i did notice thoguh that it wouldnt go into OD until it was at a certain temp

if it was too cold then it stayed out of OD automatically for a while no matter how fast i tried to get it up to

on warm days it always went right into OD at required speed somewhere around 40 miles per hour or so

temp sensor/ECM issue on yours maybe

if the bad solenoid is ruled out

or wiring plug connection corrosion or loose-ness, etc

if these solenoids use any rubber seal or any kind maybe some trans fluid seal conditioner additive may help ?

always is nice to put in higher mileage trannies before its too late and seals go bad due to age and heat




good luck