'98 sport, aw4

TLDR: drive doesn't shift up but third and 1-2 work properly
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Hey everyone, long time no see.

My jeep has been sitting for a while, about three years with sporadic driving. Finally put in a new battery and drove it during a weird winter here in Portland. On essentially the last day of the snow(thankfully) my harmonic balancer threw my belt off, but just before that, D stopped shifting out 1st. 3rd worked fine, going through all the gears.

Once I fixed the harmonic balancer and changed the oil I went back to driving it a bit and no problems. Then out of no where after ~15 mins of driving D went back to acting up. 3rd still works fine(so does 1-2), no idea how it'll drive in the morning. No CEL or anything.

Any thoughts on where to go from there?

Thank you!

 

I would start by verifying 12v at the TCM (pin highlighted) with the key on and transmission in D. I wonder if it's just not getting that signal somehow. I'll do some more reading on it, because I'm not sure what the range sensor input does for that function, but it looks like a good place to start.

The TCM is located under the dash, driver's side just above the gas pedal.