Hi,
1999 ram 1500 4x4 225k miles

Truck runs great, trans runs great, 4x4 works great. Trans fluids is nice and pink and full. Running around all day yesterday with temps in the teens with no problems.

Problem is last night temps got down to -20 with a wind chill of -45.
Started truck this morning, let it warm up for 20mins and started off to work.
Got on the Highway and noticed trans would not shift into OD. Thinking it was the trans cooler being too cold I pulled off and put some cardboard in front. Drove another 40 mins at 50mph at 2200 rims and still not shifting to OD.
Engine sounds good, lower gears shift sound good, no warning lights, temp gauge is good, oil pressure is good.

Any ideas?

 

Welcome to DF.

That is normal behavior. Anytime the transmission fluid is below a certain temp, the computer shuts off the overdrive gear to prevent damage. Should also help the fluid heat up faster, running at a higher RPM. If the fluid is too cold and not flowing well, the O/D unit can overheat and break.

Will move you to the correct location. For future reference:
https://dodgeforum.com/forum/dodge-r...ead-first.html

 

Last week it was really cold here and never once did I have overdrive. This week is warmer and now I have overdrive and it works fine. Consider it a good thing that you don't have overdrive in extreme cold weather. Means its working fine.

 

Thanks guys. I appreciate it. We haven't seen temps this low in years. Truck runs strong so I had a hunch it was doing what it was supposed to.

Was a bit agitated after calling the dealership and telling them the truck ran great but they kept telling me it could be this and that... I just didn't buy it. I couldn't get across to them that there was nothing wrong mechanically.

Anyways, thanks again

 

Each year I travel from Georgia to NW Iowa at Christmas time. My truck has run flawlessly in temps down to -17deg F but on several occasions it would not shift into overdrive... I have learned to simply pull off the road, shut truck off for maybe 2 minutes, then start it and immediately accellerate to highway speed and it shifts fine. I'm guessing the shutdown allows heat to soak the tranny enough to allow the OD to function. 6yrs ago, two separate dealerships in Iowa nearly had me convinced to let them install a new shift solenoid and pressure/temperature transducer saying that was the problem. I have since done that service myself and last week had the exact same "No OD problem" in the cold weather. After a quick shutdown, 2min wait and restart, the tranny shifted into OD fine the rest of the day.

Tom
1999 Ram 1500 Sport, 5.9L auto, 2wd with 282,500 miles. 22mpg hwy!