Electrical Problem in 87 Jeep Cherokee?

OK- a buddy of mine just resolved a whole bunch of electrical issues that my jeep had going on but evidently I still have issues going on... (haven't been able to talk to him since i got the jeep back cuz he had to go out of town for the weekend) Anyway, here is the problem- the headlights, dome light, dash lights, and heater are all kicking in & then dropping down, as in, getting bright then getting dim over & over again. The heater is doing the same thing. You can hear it running and then it runs in a higher power then drops back down to a lower power in time with the lights dimming and getting brighter.

I haven't got a clue what is causing this and now I'm kinda afraid to drive anywhere cuz I'm worried. Does anyone have any idea what could be causing this to happen? It's an '87 Jeep Cherokee Pioneer.

Were they doing that b4 your buddy got ahold of it? If not, he would have a good idea of where to begin..

Other than that, check the battery connections for corrosion/looseness/etc...
Check the cables themselves for damage.
Check the other end of the cable's connections. (ie- where the ground is grounded to the block, & the pos+ connection)
Alternator going out?

If they're all doing it at the same time, it would seem to make sense that they're sharing a connection somewhere. All ya gotta do is find it.

Could just be a fuse actin' funny... or oxidation in a connector, or ... well, alot of different things.

~good luck!

when you step on the gas pedal does that help.. ( give the heater, lights etc more power?)

could be a voltage regulator, ground wire or the alternator ( i am not sure if the alt has an internal regulator or not)]
call your local parts store

let us know

yea- it seems to help when you give it more gas but it still continues to do that regardless of whether you let up on the gas or not. i will have him check the things you both have recommended and let you know what the problem turns out to be. I forgot to mention that the speedometer and radio aren't working either. They worked before but the dash lights didn't work before and now they do. He was checking and replacing alot of bad spots in the wiring so I'm pretty happy we at least got this far along with it. Another friend of mine seems to think that some of this could all be related to the headlight switch he replaced. He said something about a purple wire that he didn't wire up when he replaced that switch a few weeks ago & he wants me to tell that to the guy who's been working on it now. That wire sounds like its in a pretty hidden spot so maybe the new guy didn't check that or something.

headlight switch could take out dash and interior lights not sure about the radio though...

it soulds like the voltage regualtor to me... go to autozone and advanced auto and they will check it for you.... you can just take the vehicle down and they will check right on the vehicle you don't have to remove it...

If you open the door to turn on the dome light by itself does it do it by itself without the vehicle running and anything else on? Do the headlights do the same thing with the vehicle off or does it do this only while the jeep is running? If it only does it while the vehicle is running the it might be a problem with the alternator starting to give out and not keeping the proper power running through the system. If it does it while the vehicle's off then I'd check connections for corrosion or looseness, check fuses inside and under hood, and check the wiring at the lights to make sure there's no problems there either. With it affecting the lights and heater sounds like possible alternator problem. Autozone and advance can test pretty good while it's in the vehicle but it also tests the entire charging system best way to test and get best results is to pull the alternator out and take it down there out of the vehicle, if you do take it down there out of the vehicle take the battery at the same time so they can test both of them as you might have a bad cell in the battery or something.

YAY! The problem is solved! I went & bought an 850 cold cranking amps monster-size battery that barely fit in the battery spot today and now all the bright/dim issues are resolved! Now, the only things left to do are to get the speedometer and the radio hooked back up!!!!

Thanks for all the help everyone! I'm sure I'll be asking more questions in the future cuz my next step is to find a kick butt sound system for it!