I have a 93 pickup, with just over 150,000 mi. I live in the midwest and it gets cold here. I use my truck to drive when its icy or snowy cause my rear wheel drive cougar is not good in that kinda weather. I have to let it warm up to full operating temperature before the automatic transmission will shift into overdrive. I know that toyota put a code in the computer to not allow the transmission to shift until it reached a certain temperature (in the haynes manual its somewhere between 130 and 160 degrees). Is it common to have it warm up completely before the ECU allows the tranny to shift? Also my truck takes forever to warm up. Is that because the thermostat is open? Do I need to change the water temp sensor? What about the ECU?