Been awhile since i've been on here, the truck's doing okay but I'm going to take it into the shop after the first of the year if this turns out to be what I think it is.
The truck shifts late. And if I'm counting right I don't think it's using the O/D I think I'm just running 3 gears. At 65 mph I am at about 3000RPMs, as the speed increases so does the RPMs but they never shift after that, I've even noticed that at 45 I'm at about 2000-2500 RPMs and it used to shift at about 45mph to be running 1500rpms about. So I think my O/D is fried, but when I turn the overdrive off, the engine RPMs increase, so the O/D is working, just not properly. Does it just need to be replaced? and if so, what's the difficulty on a scale of 1 to 10? I don't want to get myself into a difficult repair when theres two feet of snow on the ground.

 

You probably checked this already but I didn't see where you mentioned it. My trans does the same thing when it is low on fluid. I pop a pint or two in and she shifts fine again. Just wondering.

 

Mine does that too,but only when very cold(winter cold).Once the tranny warms up it runs normal again.

Does your fluid need to be replaced?(too thick or too thin?)

Just a thought.

 

I think I forgot to put, she used to only do it when it was cold, then warm up and shift normal but nowadays she never shifts, and half an hour at 3000rpms is enough to warm up the tranny, i would assume. Also, the fluid is clean, in October I did a filter and fluid change.

 

Try replacing the Coolant Temp sensor. The one with 2 wires. The computer will not operate OD if it thinks its too cold.