xj voltage issue

Ok so i have a '99 Cherokee 4.0 Automatic. I havent had this vehicle too long so not much is known about how it has been maintained by previous owners. My issue started after i installed HD Offroad no lift shackle relocation brackets. Nothing wrong with their product i may have had the cut off disc bite and then cut the trailer wire harness (whoops). so anyways i spliced all the wires back together and thought no harm done. all lights turn signals etc work just fine. nothing weird going on. so i drive it to work the next morning about half way to work my check gauges light comes on and my voltage meter is read 9 but vehicle is running with no problems so i get to work shut it down and then turned it back on to make sure it would start. it does start ( maybe a little slow or maybe im paranoid now) and when it starts volts go up to maybe 10-12? its like half way between 9 and 14. i turned it back off then go out to start it after work volts are reading that 10-12 area then a mile down the road drop back down to 9. i get home i turn it back on to make sure itll start and it does. volts back to that 10-12 area. it has been doing this since monday morning and has not failed to start or anything one time since. im short on money so i dont reallly want to go replacing the altenator if its not it or going to get a battery if thats not it either. im pretty good with a wrench and eletrical just dont know where to start on this one. Thanks in advance guys im new to this form but heard its the place to be for XJ's.
Steve

Have the battery Load Tested. If the dashboard gauge show about 9 volts, suspect the alternator. Usually the brushes are worn. You could just install new brushes. If the dashboard gauge shows 19 volts you should suspect battery/alternator cable, battery connector, or ground connection issues.

Yeah 'ya heard correctly.., this is a very good XJ Forum. You have a relatively great year model XJ.., in my mind a keeper. Consider becoming a paying member when you can so as to keep the electrons flowing.., and YOU have already gotten great advice that proves the worth of this site. By the way, welcome aboard paying, or not, lol. Me.., I study every word regards various fix-it issues, even as per different generations of the XJ. I am not nearly as well qualified as some of the great contributors here. However I am always impressed by how successful repairs can be done by following such advice from them, i.e., gaining confidence from their sharing their expertise. Happy Trails.

thanks forthe quick replies i appriciate it, i called a local store found brushes for 5 bucks so i may do that tonight. In my experince with vehicles though i have learned that coincidences dont exist. i worried that when the wires were cut it could have damaged something? i check under the hood fuses didnt see any that were blown, all lights and signals work fine, now maybe it damaged the altenator? if thats the case would replacing the brushes even help or would if have damaged something else? i know this year the voltage regulator is in the PCM and im hoping it couldnt have messed that up? ill be going to test the battery and altenator tonight before replacing anything but i dont have the cash to do a brand new altenator and serpitine belt ( mines pretty aged and has had a sqeak when the AC is on so going to do it if i have to take it off) but i also hate to take the altenator off do all the brushes and the belt and find out the diaode is blown or it was just a fuse or its the PCM ETC. bottom line is i have more time then money haha id like to check what i can to narrow it down before hand

All the taillights have fuses, so cutting/fixing a wire should have no ill effects. For $5 and some of your time, it is worth taking the risk. The last dozen folks with the same symptoms had worn out brushes or faulty alternators.

Alright thanks man I got the part left it at work so looks like now I don't have a choice going to have to buy an Altenator I'm pretty pissed but hopefully this will do it