I have and 87 xj renix 4.0 and my tcm fuse blows out from this little cruise control disengage switch and I can't figure out why.....I also don't have overdrive I think they might be related Idk....my tps is good I checked that I've checked the ground that lil switch goes to and that's good Idk what else it could be...I'm pretty familiar with the xj but I'm stumped please any help would be great!! If I disconnect it the fuse will. Hold up but my cruise control doesn't even work anyways but my biggest concern is the overdrive isn't working. When I go 75 my rpm is between 2500 and 3000 I could be crazy but I think its suppose to lock in just under 2400 Idk is there anything else I can check? ??? This whole thing started when I decreased and power washed the motor I was in a car wash so I had to drive it right away after that it wouldn't shift right and the motor wouldn't even shut off ....well I did some wire chasing replace pretty all of the yellow wire that run from the tcm to the fuse panel and got it to shut off like its supposed to now my od doesn't work and that dam switch that keeps blowing my tcm fuse it doesn't blow if its unhooked I did that now my torque converter won't lock in goin 75 Idk .......

 

I would start looking for a short in the wiring. But as mine is a 5 speed I can say where. Sorry

 

Anything will help

 

My brother has the same problem and the same cause got back from wheeling and went to the car wash and sprayed down his engine bay went to drive home and the over drive wouldnt work, cruiser54 told me that in the older models theres ground issues. tell him your issue and he will send you the diagram.

 

forget what i said above, your problem is the "torque converter clutch sylinoid" this will fix your over drive problem.

 

And for the Transmission control module, there should be a 15A fuse, this fuse powers more than the transmission module, let me know if it pops immediatly when you put it in. that should about sum up your problems! let me know how it goes

 

First off, how did you check your TPS?
Verify please that the fuse up under the dash by the TCM is blowing or a fuse in the fusebox.

Keep in mind that the cruise control uses the brake light switch to disengage the cruise and if the TCM sees the brakes applied, it disengages the overdrive. See the correlation there?

Also, do us all a favor and use punctuation in your posts. That texting like crap is rough on us old guys.

 

My bad^, my friend bought a cherokee without Over Drive and replaced the transmission converter clutch sylenoid and he said that solved his problem.

 

*Torque Converter Clutch Sylenoid*