hotdawg22

Hello all. New here and am having serious problems with my 2003 Jeep GC and the battery goes dead overnight.
Replaced the alternator cause i assumed it was not charging the battery, that was not the case. Then the battery proved to be good (but) so i replaced it as well. Still goes down overnight.
When i touch the negative cable to the battery post it sparks so that tells me that there is a short somewhere, but where?
So maybe somebody out there can tell me just where and how to find this serious short. So whatever it is , it is doing so without the key being on.
Thanks,

dave1123

Welcome to CF!

Connect an ammeter between the negative battery post and the negative cable end. It shouldn't read more than 1 amp. If there's more flowing, start pulling fuses until the flow drops. Whatever that fuse controls is your problem. Check the interior fuses as well.

Clue; if you have an aftermarket radio and/or amplifier, pull that fuse first.

The 1 amp mentioned earlier should be for the PCM memory and radio station memory. It'll be less, but I'm being generous. I think it's around 700 milliamps or 0.7 amps.

hotdawg22

OK, thanks for the reply. I haven't done that yet but i just got finished with using a TEST LIGHT theory i read on the internet. Says to connect the light between the negative post and the cable and then start pulling fuses and relays. When light goes out then that is the circuit that is shorted.
Well i did that for all the fuses and relays under the hood... nothing.
So tomorrow i will start with that fuse box under the dash and hope it will show up there.
The whole concept on this is very confusing and i miss the good ole days when you could just trace that short or look for a blow fuse and bingo.
Anyway, my question is here... if there is a short in a FUSED circuit, why doesn't the fuse just blow?? LOL
I appreciate any feedback on this cause the only way to keep this jeep running is i hook up a charger every night to keep the battery going.
Thanks again.

dave1123

If it's a dead short, the fuse will blow, but if it's just a drain such as an accessory that's actually still on, like an amplifier, or something stupid like the canister purge solenoid, it can get difficult to find. On an older car, I've seen the glove box light draw down the battery over the weekend! Another one is the underhood worklight.

Brain fart! Do you have the tow package? It could be the tow lighting module. These have been known to be a problem before, especially aftermarket ones. The brakelight circuit is hot all the time.

Then you get into the weird stuff. 86 Ford Ranger. a harness splice under the battery was full of salt corrosion and was doing a slow cook all the time. When we found it, it was as big as a golf ball and warm to the touch.

hotdawg22

It doesn't have the towing package but i will check out some of those things you mentioned. Could be something strange as you mentioned cause i been smelling rubber burning for a long time, long before the battery started going down. I was never able to locate it and maybe it just got worse and burned thru to ground?
Do you know if that taillight circuit is on all the time and unfused? I know you did say the brakelight system was on all the time. That could be the problem. I guess there are all sorts of things it could be and wish i just had the technical knowledge on what to look for.
Anyway, thanks for your thoughts.