When it's cold outside like it was this morning at 5 degrees. The transmission won't shift into overdrive. This is a new Jasper transmission too, with about 7,000 mile on it. The old trans did this too. Today I drove about 100 miles before it would shift into over drive. But on my way home from work it worked just fine, and temp only got up to 10 degrees today. Is this normal or should I take it into the shop and have it looked at?

Oh yeah, it's a 98 1500 sport with a 5.9 Automatic if that makes any difference.

 

mine did the same thing too it was about 10 here also but i believe the tranny temp has to b above a certain degree in order to shift into O/D but im not positive

 

i believe your trans has to be over 50 degrees to be able to shift into over drive..dont know if thats the exact temperature...but i think its somehwere around there

 

Yep, mine does it too. It won't lock the TC until it warms a little bit either.

 

There's a temp valve in the trans cooler line. If it is cold, it won't open so it will build heat in the tranny fluid. If the fluid stays cold, I wonder if it won't allow it to shift as well. So, if that valve is not functioning correctly and is stuck open, you're cooling already cold fluid and it's never building enough heat. Just a guess. I think a code might throw if it stays too cold for too long (37?).

 

The PCM prevents engagement of the converter clutch and overdrive clutch when fluid temps are below 50 F.

 

Yeah, But for a hundred miles? Will the transmission fluid warm up while it's park? I didn't warm the truck up before leaving for work today because I was running late. Will it help If I let the truck warm up for a few minutes be for I take off on cold mornings?

Tomorrow morning will be below zero. I'll try and let the truck warm up before I leave. We'll see if that work out any better.

 

Yeah, 100 miles is quite a bit. I live in AK, and have had mornings where I've driven it in -20 degree weather. I usually go out and start the truck 20-30 mins in advance each morning to let it warm up, and on those -20 days, if it's been idling in the driveway for 30 mins or more, it'll usually shift into OD. But if it hasn't been warming up for very long, it sometimes won't shift into OD.
But 100 miles? Way too long IMO.

 

-5 at my house yesterday and my tranny acted the same way. Drove the 32 miles to work without OD. When I left work about 9 hours later it worked fine and the temp was only +8.

I did however let my truck sit from Monday afternoon until Wednesday morning. Wondering if that had any effect.

My tranny was built by Dr. Evil and has less than 10,000 miles so I wouldn't worry about it being a Jasper thing.

I chalk it up to just being my obstinate cold weather disliking Ram.

 

This morning, +13 degrees and 10 minute warmup = no issues. Shifted right into OD without an issue.