I have a 94 Dodge 3/4 ton with an automatic transmission. It will not shift into overdrive when the temperature drops below about 35 degrees. (In SW Colorado this is a common occurrence) I have heard this happens to others as well. I have also heard this could be the work of a malfunctioning TPS. I hope to spend some quality time in the shop the weekend trying to figure this out. Any suggestions would really helpful. This is my first post to this site. It looks like there are some really knowledgeable folks out there!

 

You are correct, the ECU will not allow a upshift to OD or lock the converter until fluid temp is at 70F, I found this out the hard way when I first bought my truck from a friend and on a cold morning I pulled out into busy 75-80mph freeway traffic and had 2 cars nearly rear end me and they blow past me in the bike lane due to me going so friggin slow sitting at the governer in 3rd gear- some even think im being a jerk and flip me off but oh' man its "GAME ON" once it locks the converter in OD

 

Thanks Joe, got to love electronics!

 

no prob, plugging the truck in fixes it. I also remember reading about how to bypass the temp sensor on here a few years back too- here is mine at 40F, it warmed up quick http://www.youtube.com/watch?v=MTjxks1nJVo

 

I think your temp sensor is in the fluid line to the cooler as mine was. Mine is pulled and a 10K, I believe, resistor is now across the pins and sealed. This lies to the computer and lets it shift. You must be VERY careful on cold days as it can be very hard on the tranny if you shift too hard when it is cold. Do a search here and find the info you need. It's been a long time on mine and I am not sure of the resistor value. I used the temp port in the line for my tranny temp gauge.

 

Unplug the tranny temp sensor from the cooler line, jump across the socket with a ten k resistor and drive on....

 

1k (1000 ohm) resistor.

Dodge had a fix for people with this problem that they would do for free for new owners in cold climates> http://dodgeram.info/tsb/1995/21-03-95.htm

 

Thanks for the info all! I plan to bypass the temp sensor this weekend. I'll let you all know how it goes.

 

PS Carl, It's not junk paint, it's Snow Camo!

 

Except for the rust!!!!