1995 Jeep Cherokee overdrive

I have a grand cherokee and the overdrive light stays lit after I start the car. Then upon driving the car will not shift into overdrive. However when I stop and turn off thecar after it has warmed up the lite goes off and the car runs like it should. I have had a trans service with filter and oil change, no noted problems with metal or contaimetes in fluid. Local trans shop here coded several things on the trans and replaced at the tune of 500 dollars. Problem still excist. When ever the car is warm the lite goes off upon start up but if its cool or cold the lite stays on untill I turn off the car and restart after its wamned up.

Steve