Hi all been having an electrical issue lately and been trying to fix it with few words of advice and very little know-how for where to start...1999 jeep cherokee sport

My issue (excuse the rambly jumbleness): It started out every once in a while i would click my lights on (running or actual headlights) and the rear wiper would switch itself on (noticed it one time when it was raining out)...then the other day i was driving switched my lights on and bam stuff started going crazy:
-airbag light went on and stayed on
-rear wiper was going by itself
-rear defroster was on
-rpm gauge stopped working
-cel came on after no bus appeared on odometer
-then turned headlights off and bam everything went back to normal

couple days later i tear into my dash looking for electrical issues (tried a new headlight switch changed nothing then unplugged cluster to see if it was bad wasn't) then went behind the left rear interior panel where the taillight harness is and found a loose ground so fixed it...thought problem was fixed but that night went to the store and it repeated the problem but while it was spazzing something like clicked and it all stopped and my center console lit up (didnt notice it wouldn't light up when everything was spazzing)...couple days go by and it continues to spaz and stop when i turn lights on...

then one night i turn on my dome light and my center console lights up and rear wiper defroster switch on and stuff spazzes...next day plug my phone into the aux 12v outlet and stuff spazzes for a couple seconds...well anyways last night i forget i have the issue and go to the mall coming home at night turn lights on problem doesn't go away and i notice my blinkers/ hazards / dome light/ center console lights don't work when the issue is occuring so i turn lights off fearing electrical fire and drive home with hazards on....


so in lamence terms when headlights are switched on stuff goes weird...when overhead dome light switched on stuff goes weird...without those two on everything works normally except the rear defroster won't stay on...


please help i just spent two hours under my hood cleaning grounds cause those were the few words of advice were to do


ps..dont know if its of correlation but i have a water leak that leaves small puddles in pass. floor when it rains

 

Everyone has that leak... Not gonna be a issue... Everything ties into your.fuse box... They have been known to corrode easily... So does the ignition switch... switch not the tumbler and keys... Id look there... On my 89 I had to replace every fuse when i got it cause they literally were rotting ad falling out on my foot when id hit bumps... After research i found out I was not the only one... Try those two areas... Clean up the fuse box front and back (pita) and change the switch on top of the column down at the base...

 

When you cleaned the grounds in the engine bay did you clean the ones near the PCM (see pic).

 

yeah i pulled them apart wire brushed where they sat then sandpapered the terminals then gooe'd 'em up with dialectric grease and bolted them tight

 

Run a new ground wire from battery (-) directly to the chassis. #10 wire or so. Find a firewall screw, scrape to bare metal and attach there. Another from battery (-) to the headlight ground screw. See if things change.
Also check your battery terminals/clamps if you haven't.
Sounds like voltage is backfeeding through oddball paths to find it's way back to the battery.

 

i made new custom neg. battery cables the smaller one is 6gauge and the main is 4gauge cause old ones were corroded