I have a 98 xj 4.0 automatic. I went wheeling the other day. On the way home my lights started getting bright then deem over and over. Pulled over when i saw the volts gauge naxed out. I restarted it and started to go my head tail and brake light all blow. I towed it home pulled the alternator it checked ok and so did battery. I then tryed to wire in a 86 dodge voltage regular. No luck it then act as a bad alternator. PLEASE ANY IDEAS??? its my dd.

 

Voltage regulator is in the PCM.

 

Yeah hear u can put a external one on there

 

Just curious.... How old is your battery?

 

9 of 2011

 

Two main things cause overcharging. One is a bad internal regulator which means a new alternator. Another is a load short condition in the battery. Have both tested and replace the offending component.

It is possible to install an external regulator to correct the alternator related condition, but I would not recommend doing so if this end up being the bad component. All you would be doing is to temporarily fix something that is going bad to begin with. The "one wire" charging systems are internally regulated within the alternator and are not designed as the previous generation "three wire" systems that had to be externally regulated. I really don't believe that you would be doing yourself a service jury-rigging a fix when the proper one is not an outrageously expensive one to begin with. I had a customer with a Ram truck that had a similar issue and he installed one to fix his problem. It worked, but I believed that he had wiring problems that were the culprit and is facing worse issues down the road by doing the quick fix. I don't think that wiring issues are something to be concerned about in your case, though.

 

Oh yeah, just because a battery is only a year old doesn't mean that it wouldn't become defective. Have it tested.

 

I had both alernator and battery tested at local auto parts store. Both were good. Reglator is in computer also.

 

Can one of regulator wires have short to some 12V wire?
I would check voltage between regulator wires but I need to know what kind of voltage they should have.