here is the deal, my voltage reg. went out in my 91 yj,and it is built in the computer,NAPA guy says it is not rebuildable,new is too many $$$,all the salvage shops I have contacted are a no go.I need help fast as possable,I done a search and done no good . 1991 yj 4.0 auto thanks in advance

I went to Kragens and believe it or not, they sell a computer for a YJ (in my case an 87 with 4.2). Give it a try

You don't have to stick with a '91 pcm. You should also look for a '94-'95 pcm while you are in the yards. These are better than the '91-'93 pcm's because they have much better block learn functions, and have a larger window for fuel trims. Just make sure that you stay with the same type of tranny. ie, auto, standard. An auto pcm will work, however will set false codes for torque converter lock up. (at least in a XJ with a aw4, I don't know about a YJ) Some XJ pcm's will also work, but may have added functions for cruise.

Chrysler sells a reman pcm for a reasonable price, somewhere around $175. These pcm's will automatically detect and turn on different functions as they are used. ie, if your YJ has a/c, the first time you turn on the a/c, that function in the pcm will activate.

Another possibility is wiring in the old two wire pancake voltage regulator that Chrysler used on the mid '70's. The only drawback to this is the fact that the "check engine" light may come on, and the "battery" light on the dash won't work.

thanks for the replys,another ? the chips that you buy like (JETS)do you still use your stock computer with them or do they replace your orignal,if they replace,why not go for some extra hp. thanks

I think the jet chip sandwiches in between the harness and the pcm. So you will still need your stock pcm. Of the two jet chips I have seen on Chrysler products, none of them worked. At least not enough to show any significant hp gain. I personally think that they are a waste of money, at least at high altitude where I live.