Etherel15

After not touching my 1996 Jeep XJ in about a week, the battery was completely drained. Thought it was due to working on the headlamp switch + harness upgrade, but found out that my headlight fuse had burned out while the jeep had just been sitting there (lights were switched off I assure you). When I replaced the fuse, the blades sparked when I put the fuse in the box, and very oddly, a bolt on the metal frame supporting the fusebox was also sparking! In fact, just touching it with a screwdriver brought more sparks. Here's a still from a video I took:


Now I assumed my fuse problems previously had been to the POs LED headlights, as detailed Here (seems to be working fine atm, not closing it up till inget this fuse problem sorted tho), so I've already replaced the headlamp switch in the dash and installed an aftermarket harness upgrade to power them directly off the battery, and made sure the headlights had tight clean grounds. But apparantly there's still more mystery to why my headlight Fuses keep going bad.

can anyone tell me what's going on? What do I do? I'm horrible with electrical. Thanks!

Sworvoo

What was the fuse you blew rated? I’m guessing it’s not a 5 amp or less?? It sounds like you have a short that is not a dead short. Like it’s shorting to rusty metal causing a slow drain until you move something and the connection improves / short gets shorter, and then the current exceeds the fuse and pops it. Sometimes heat from a bad connection can change resistance as well so a slow drain can develop into a short. Hate to say it but you likely just installed something wrong.

Etherel15

Its the big orange 40amper. I'm fairly certain this problem is a previous condition. Only recently got this jeep and went through 2 other fuses before trying to "fix" the headlight issue. Guy I bought it from even had to jumpstart it, and the headlights had a dead fuse then lol. That fuse has sparked each time I've put it in (not sure about the frame bolt, it was more buried before). I installed that Headlight Harness upgrade, but that just feeds directly to the battery with its own in-line fuse (which hasn't burnt) so if anything it would take load off the fuse box right? And the jeep was having this electrical problem before I worked on the headlights and switch. I think your right about a short of somekind, But I lean towards pre-existing. Wish it was my mistake because that would limit whats wrong!

Is that bolt supposed to be a ground, but its rusty enough its causing problems, or is that bolt NOT supposed to have any electrical connection, and theres a short? If there is a short, how would I go about best trying to find/fix/solve it?

Sworvoo

Well everything metal is generally a ground. I would assume that the issue is not directly that the bolt is sparking. It should be cleaned and tightened but that won’t solve the real issue. Sorry, not sure where to start on this one.

Etherel15

thanks for responding at least. Atm I'm not sure if that's supposed to even be a ground, or if the short is just using that point to "escape". But I figure a ground wouldn't spark like that if it wasn't connected well, so I'm guessing that shouldn't be a ground. Does that mean the short is in/near the actual fuse box, and its exposed to the metal there??

Going to try unplugging a few lights to see if I can narrow it down to a specific endpoint. If not I'll be at a total loss of what to try next.

arpunk

Do you have access to a multimeter? If so, how much current is the Jeep drawing with the key out of the ignition and all accessories off?

If you can consistently get that bolt to spark, I would do some testing around it to see if you can isolate the circuit. Does it spark with the engine off? Can you get it to stop sparking if you pull a fuse? If you can get it to stop sparking with a fuse pulled, your short is somewhere after the fuse box.

Etherel15

It only sparks with the #13 Fuse (Lighting) in. When removed there's no sparking, so its definitely after that fuse. It stil happens without the key in ignition, and the doors/lights off. I think it comes down to is it in the Power Distribution Center (past that fuse), or is it somewhere along the wire harness? Today I attempted to disconnect the Headlamp switch, the headlights, foglights, and rear lights. But that didn't stop the sparking. Can anyone tell me everywhere the #13 Fuse (1996 jeep XJ) leads to besides those? Or how to test the wire harness without ripping the entire thing out (Its lighting and it goes EVERYWHERE annoyingly)?

I'm hoping to get a multimeter tomorrow, and I'll try to test loads. Seeing how it sparks and the battery drains without the key in, I'm leaning towards there being a constant phantom draw. but I can get confirmation when I get a multimeter.

arpunk

You can get a multimeter at Home Depot and return it if you like, but it is a tool that will come in handy down the road so I would hang onto it.

To see how much current your car is drawing… with the engine OFF and all accessories off, remove the negative battery cable. Set your multimeter to DC AMPS. My multimeter has an auto range function so I don’t need to set that. Connect the multimeter between the negative cable and negative battery terminal. You want to see around 40-60mA depending on how fancy your car is. I would bet you’re going to see a lot higher. Since you suspect that something on the headlight circuit is causing a parasitic draw, make note of how much the current drops after removing the trouble fuse. I don’t think that circuit should be pulling any current with the car off.

I would start at the easiest areas: headlights, taillights, etc. Check for any bare wire. Check any connectors and maybe give them a good cleaning. Hopefully it’ll be easy to find but tracing electrical gremlins can be a real pain.

Etherel15

oh man thank you for the detailed information! I really appreciate the extra info, I'm so new with this stuff. Got the multimeter, but family problems occurred, then the below freezing snow kinda killed my weekend repair plans. Got as far as replacing a wire ring terminal before **** hit the fan, so it'll have to be a monday project. gonna try to learn basics of how to use the multimeter, and then go with your instructions. Had someone suggest a circuit tester probe, but he's more clueless about car stuff than me, and it looked like it was a poor-mans multi-meter (but hey, I'm both poor and unknowledgeable so maybe its designed for me).

I'll give more updates monday. Battery still has a small drain to it, put it on a 30 min float charge. The fuse/bolt isn't sparking at the moment when its inserted, but when you tap the bolt with a screwdriver it sparks (only with the fuse in). So still shorting, but it seems to be maybe more of a loose/fraying situation (would explain going between fine and full fuse death randomly).

Etherel15

Update: Took the multimeter out and only got a current of about 9-10mA between the negative battery terminal and the negative cable. I even took out an old IBM analog meter my grandpa used like 40 years ago, and got what looked like 10-11mA. Regardless, I tried taking out every fuse in the PDC box, and didn't get a drop off any of them besides the big 60A which I believe is engine ignition (dropped about 3-4mA). Didn't check under-dash fuse box, it hasn't had any problems, it would be quite annoying to check every fuse back and forth, and honestly the current was only showing as about 10mA anyways. Battery voltage was a bit low at 12.2V tho, but haven't wanted to replace the battery until I wasn't have these electrical issues.

One of the first things I did before I could get and use a multimeter was I unclamped the PDC box, lifted all the covers, and tried to get a good look under it. I inspected where the big cables went in and all the wires went out but didn't notice anything discernably wrong. Did find out the whole thing was just a big plastic box, sitting on a plastic bed with clips, connected to the vehicle frame on the metal stand thats bolted down at that one sparking bolt. I didn't see anyway a wire at/near the PDC could be shorting to the frame, and I'm certain now that bolt isn't used as a grounding spot (but as its bolted to the vehicle, it is groundable/shortable TO).

Maybe unseating the PDC box, wiggling the cables, and clipping it back in was part of the problem, but it was after this that I got a multimeter, and couldn't find any drain. Previously I could often scratch the metal around that sparking bolt to elicit some small sparks with a screwdriver, but I couldn't when I tried today. I used the circuit tester probe to make sure every fuse was working, tried checking as many ground wires as I could find. Everything came up good except one 40A fuse that I have no idea how long hasn't been working. Its Fuse 4 (3rd up from the bottom left) and I think, according to this FSM its for...Anti-Lock Brakes? Which is odd that A) theres a fuse there, when this jeep never had ABS B) no ABS relays, just that fuse, with socket clips when other unpopulated slots don't and C) the fuse is dead. I even checked it with a continuity test on the multimeter. So thats a mystery.

*EDIT* Closer look at a diagram its Fuse 5 thats ABS, and Fuse 4 goes to the Fuse Box and Circuit Breaker 16, Fuse 11, and Fuse 13. These control a lot of stuff I'm not certain entirely, some of it I don't think I have. Trailer Tow connector, Power Seat Switch. Some I'm not entirely certain what they do, Stop Lamp relay, Headlamp Delay Module. Some that I thought were working, Horn Relay, Power Door Lock/Unlock. So now I'm just more confused. Added some diagram pictures I'm looking at trying to figure it all out.



Any clarity on what Fuse 4 does, and how I didn't notice it not working? Or anything else for that matter lol. Not sure if I "fixed" anything, or if its just intermittent and will pop up again randomly. If it does, any advice on how to chase it down then? I guess for now I just wait until the next time the jeep tries to kill itself in the night or when parked, and then break out the multimeter then and hope I can find something?

arpunk

@Etherel15 10mA is a perfectly acceptable amount of current for your Jeep to be drawing with the engine off.

With regard to the fuses, I'm having difficulty figuring out if the fuse you are talking about is ABS or not. Do you have a cherokee or a grand cherokee? Is your fuse box labeled?

Etherel15

1996 Jeep XJ. Sorry, the original fuse diagram I was looking at had F4 and F5 next to each other and I followed the wrong line to the ABS. Fuse 4 goes to a set of different fuses/circuits (as I edited my post above) so forget the ABS stuff lol.

10mA is great! But then it leaves me with the gnawing question of did I somehow magically fix the problem, or was it just hiding today, and it'll strike again later

arpunk

Fuse 4 should be “flash to pass” AKA briefly flashing your brights. Should be a blue 15a fuse.

If that’s the problem fuse and you don’t want to spend additional time troubleshooting, yank the fuse. I think you should still be able to use your brights but you’ll have to push the lever forward to turn brights on and pull it back to turn brights off instead of being able briefly flash the brights. I don’t use that function often at all.

You may have put a temporary bandaid on the problem for now but if wiggling some wires fixes a problem, that means you’ve got a problem that you’ve only rectified if nothing moves. Think of it like a ball being balanced on the end of a stick. As long as you don’t move the stick, the ball won’t fall, but if you move the stick, the ball falls.

If you’ve got an exposed wire with voltage running through it and by messing with the fuse box that wire is now 1/4” from a ground, all it takes is a bump that jostles the wire enough for it to make contact with or arc to a ground. It’s a very iffy situation.

If pulling the fuse 100% solves the problem and only affects your ability to flash the brights, that would be the easiest fix if you don’t mind losing that functionality. I would still want to know what’s going on that’s causing the problem because it may affect more crucial vehicle functions depending on what’s going on.

Etherel15

This is Fuse 4 in the PDC under the hood, not Fuse 4 in the fuse box under the dash. It was a big orange Maxi 40a. Diagrams above say Fuse 4 controls my power doors and horn (and Trailer connector, Sentinel headlamp delay, and power seats I don't have). Guess I haven't locked my doors in a while hah. The fuse that caused issues before, and was blowing every now and then, was Fuse13 for the headlamps. can't live without that sadly.

Yeah I'd rather just found a problem and fixed it and feel better at least believing the problem was fixed, now I'm just waiting to see if it happens again, and some frayed wire just happens to wander too close to a metal wall. Outside of tearing apart all the wire harnesses coming in and out of the PDC I don't know how I'd find it tho.

arpunk

Oh I see - sorry about that! I was wrangling three dogs while responding.

If the problem fuse is the headlights, have you tried inspecting the headlight harness connector? In my 1990 it is just forward of the air box. In your 1996 it should be in a similar location. I would give that a good inspection, clean out all the old gunk, and make sure that the connections are tight.