This just started happening on my 1997 cherokee. When I step on the brake pedal the front turn signals and dash lights go on. Thinking it was a bad tail light bulb back feeding the system I pulled the bulbs. No change. Sockets look good too. I also noticed when the headlight switch is on the tails are at full bright. As if you were stepping an the brakes. Before I start pulling things apart any areas I should check first? Would a bad headlight switch cause this?

 

Hmmmm. I'm skeptical of a bad headlight switch causing that. I'd be looking at that headlight grounds first, then all of the lighting grounds.

 

is there a diagram showing where the grounds are located?

 

Yes indeed! CCKen has posted several. Search on his name and "ground" and you should find it. Here's the location for the rear lights:

https://www.cherokeeforum.com/f2/rig...2/#post3232179

I know he's posted the engine compartment grounds many times, too.

 

Had time to mess with my cherokee. I don't see the ground that goes under the passenger seat? I pulled the plastic trim off of the passenger side. The wire bundle looks to go straight back and then split under the rear bench seat. There is a ground there. I checked the grounds on the drivers side front fender well, under the drivers rear quarter cover. Pulled the headlight switch, brake light switch. Pulled the side marker and tail light fuses. disconnected the passenger taillight connector behind the passenger side rear plastic quarter cover. Still have the brake lights on full in any headlight on position. Front turn signals also still turning on when the brake pedal is pressed. Is there anything in the steering column to check? The problem was intermittent for a couple days and now is a problem all the time.

 

I had a similar issue. The ground is screwed into the support that the seat bolts onto. You have to remove the seat and pull back the carpet to see it. No surprise that this area is prone to rust!

Aside from that, the tail light assemblies ground behind where the spare tire sits. Remove the plastic panel on the left side of the cargo area for all of that electrical stuff.

 

Passenger side grounds.

Attachment 304965

 

after football i spent a few hours on grounds, one of the top 3 topics it seems,ground,rust, and starters!
everything that runs on +12v ends up getting grounded somehow.
the+12 starts at the batt and goes thru circuit breakers,fuses and/or switches at the top of the wiring info with various colored wires.
ground goes to all items thru a black wire that makes the rounds ALL OVER THE TRUCK. the gnd wire may be spliced or go thru connectors but it goes everywhere and is connected to the metalic part of the truck at various points.
it is best but not crucial that every screwed point be connected to the body/frame. its a big long wire so everything gets grounded.
being "grounded"to the body minimizes noise along the ground path.
for lights and most stuff as long as the wire is not BROKEN OR CUT all should be well,
. the important thing is you dont have to find every one of hundreds of ground screws to fix something.
if you can verify that the black wire to your device is solid like with an ohmmeter or a test light hooked to 12v+, you have ground.

its not hundreds of individual ground wires! to worry about.
its a ground circuit that started out all tied together.
i noticed as i read the post that g303 in my rusted 2000 was hanging there with the seat bracket rusted away!. the wire was solid but the ground eye and screw were long gone.
so theres a lot to know about the "bottom "side of the system but i think, not as big a deal as thought. the black wire condition is more important than the screws that tie it to the body/frame.
the system does not depend on electrical conduction thru the body, but thru the black wire. you will notice that wire size is shown for all gnd wires and they all end up back at the - end of the batt.

every item does NOT have its own ground screw.

 

It's not a truck. It's an SUV.


Not quite right. You can have ground, but not have adequate ground. Corrosion may allow some current to pass, but not allow sufficient current for correct operation. Things can get really weird then.


Completely wrong. It's a series circuit. A failure at any point is a failure in the circuit. The condition of every component, wires, connections, screws, and the body itself, are all critical.

Completely, badly wrong. The body is the return path. The black wire is just a connection to that return path. The body is the conductor that carries the current back to the battery. (Or from the battery, depending on whether you are talking about electron flow or hole flow, but no need to get complicated.)


Every item eventually goes to a connection to the body somewhere. It may join with other electrical devices and share a ground point, but every electrical load must have a ground point or it won't work.

I know you mean well, but it's clear you have no real understanding of electricity. Please refrain from giving advice on the matter.

 

64 years of working with wire, tubes transistors microchips, programming cpus.

wire yeah!!

 

are you sure? Haha mark has some serious points man.

 

So you are in your eighties? I don't think so. I think you are just flat lying.


You obviously don't know even the basics of electricity. You don't talk like an engineer or technician at all. In fact, you come across like a know-it-all know-nothing kid.

 

came here to learn,,,help,, and have fun,,not argue or insult anyone.
born 1942, built crystal radios at 10 yrs, learned color code and ohms law,never looked back. been soldering wires ever since...sorry if my observations of the wiring diagram of my 00 bothers you.

 

Your in your 70s? Pretty sweet man that your here learning....you must be in good shape if your able to crawl underneath your jeep so much to jump your starter....if your not lying, props to you....but your thing about black wires in this thread are still highly suspect haha

 

Keep it civil please guys. The XJ grounding network has many branches and is renowned for being extremely marginal. G303 is the problem here. I'm sure the OP isn't in this for an argument.