1993 D250 Automatic
I’ve been having trouble with my transmission dropping out of O.D. for about the first 5-10 minutes of driving on cold mornings. Once it warmed up it did fine. It didn’t really bother me too much because I would just let it warm up before I drove it and it is a second vehicle (my primary is a 94 CTD) so it didn’t get driven much anyway. I am about to try to sell this truck so I figure I better get it fixed because no one would want to buy it like this.
My static TPS voltage was .48. I adjusted it up to .8 and drove it about 7 miles. Everything was fine and I was feeling good about how quickly I had fixed the problem when it started doing it again. I have adjusted it in .1-volt increments between .5 and .8 and it doesn’t really seem to change the problem. If I go above .8 it won’t go into O.D. It seems to shift into O.D. fine no matter what setting between .5 and .8 however it drops out when you let off the pedal. After my last adjustment I did think to check the range from static to wide-open throttle. At WOT I was reading 3.4 vdc. As I slowly let off, the decrease in voltage was steady until about ½ to 2/3 travel and the voltage jumped to almost 5 vdc. It looks to me like the TPS is bad but I just wanted to get some opinions from you experts out there before I drop the $ for a new TPS on a truck that I just want to get rid of. And one last note, I did remove the TPS and clean it with contact cleaner to no avail. Thanks in advance for the advice.

 

There is a temp sensor on the tranny that locks out OD untill the tranny is warmed up. My truck will not upshift to OD for about 5 mins on a cold morning.