89 renix xj help

So I am actualy posting this for my dad his xj all of a sudden won't shift Into passing gear it was absolutely fine then all of a sudden starting acting this way he's ran through all the vaccume lines and replaced some cracked/broken ones there's a vac line that runs to the tranny and he said it was in good Condt no breaks or cracks what could be keeping it from shifting is it a throttle cable adjustment or something ? PleAse help he's trying to go camping with the jeep in a few days. Your input would be greatly appreciated! Thanks . Happy trails!

So by passing gear, you mean it won't down shift?

If that is the case, the most likely problem is the TPS. Didn't perhaps wash the engine did you?

Basics....check the fluid level, check the TV cable, check the TPS.

Now if you mean it won't go into overdrive, that's a different situation. The most likely cause of not shifting into overdrive or locking up the torque converter are because of a bad or missadjusted switch on the brake pedal.

Correct yes it won't downshift... That makes perfect sence. What is the location of the tps I'm assuming it's on the throttle body

Yes it is on the throttle body and it MUST be adjusted when replaced.

Do not forget to check the fuse at the trans control box under the passenger side lower dash.

I just had a major issue with my 89. I just moved from NV where my jeep never actually saw anything resembling real rain....to Wisconsin where I just drove it in it's first rainstorm.

The transmission started behaving exactly as if it were in 1-2 regardless of whether it was actually in 1/2 or D or Overdrive. I did some roadside redneck repair by pulling the 10 amp fuse on the TCU bundle and then limping it home manually shifting through the gears and neutral when necessary.

I assume and am hoping that someone here can possibility confirm that my problem could arise from a wet TPS sending a false WOT signal to the TCU? And if so, why did pulling the fuse on the wire bundle help the situation?

and yes, I have a "modified" hood....I'll have to fix that...and my leaky sunroof....damn weather.

mr voltmeter can help: