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Help! Replaced main cables, big 3, new battery, issues
Just got my first 98 XJ about two weeks ago and have been doing some basic maintenance stuff. Just as I get everything buttoned up and about to start it up I'm having some big problems.
I decided to replace all the corroded cables coming off the battery, do the big 3 upgrade, and throw in a new Odyssey Extreme 34-PC1500T. I did tons of research prior, cleaned all connections, and did everything carefully one at a time. Now I am having issues when plugging the negative terminal on the new battery, getting sparks and popping the inline fuse. At first I had the alternator + connected directly to the battery +, with the stock cable from Alt+ to PDC. That cable blew up when I first tried connecting the negative terminal, and it also blew the inline fuse. After that I connected alternator to PDC, and it's still popping the fuse. I triple checked all the connections and made sure everything is where it should be. I really hope I didn't mess up some components . I am new to all this electrical stuff and am at a loss....
How do I figure out whats going on and fix this?
I replaced:
Battery + to Starter (4AWG, re-connected existing smaller green cable to starter)
Battery + to PDC (4AWG)
Alternator + to PDC (4AWG with inline 200AMP fuse)
Battery - to Chassis (1/0AWG)
Battery - to Engine (1/0AWG)
Battery - to Alternator - (1/0AWG)
Engine braided ground coming off the back to the firewall (1/0AWG)
The alternator is grounded through the case, which is bolted to the bracket which is bolted to the block. Hence the battery to engine block ground. Same reason why the starter has no ground cable. It’s frounded through the case which is bolted to the trans etc. One could run a cable from the alternator case to the battery and this would eliminate some resistance but is not necessary. Where you have the cable connected from the alternator to the negative post is not a ground.
Wow, I made this thread over a month ago, it just posted today! I guess since it's just my second thread.
Anyway, I figured out what was going on shortly after typing it all up.... Turns out I just forgot to put the little isolator back on the positive post on the alternator... It was shorting out right there on the alt case
Are you sure that's not a ground on the alternator? I looked it up in the service manual:
I think there is a ground wire from that alt- plug to the engine ground spot stock. I just beefed it up straight to the battery, thought it might help.
It may be there to the block. I didn’t replace it on mine so im not sure. I didn’t see it listed as something that grounds in that location and I doubt the service manual is wrong. That’s the only thing I saw that was different from mine so I just assumed.
I was going to say, one of your positive leads was probably touching bare metal somewhere - causing a short.
Or a negative lead was somehow touching a positive cable, but that is less likely since they are fairly well isolated.
Glad you got it figured out!
EDIT:
On my 98' - there is a ground cable connected to the alternator case. I upgraded my alternator to a Durango alt, and ended up making a short 'jumper' wire because I couldn't connect it to the same spot as the factory alternator.
Plus I have a beefy ground to the back of the cylinder head - for some reason was easier than running it to the posts by the distributor but I can't really remember why right now (maybe I just bought too much cable, lol)
Last edited by investinwaffles; 11-13-2018 at 07:42 AM.
I thought about it after I posted. That ground on the back of the alternator is not where the alternator itself would ground to. It’s the ground for the regulator or something like that. It’s like I said, the alternator grounds from the case, through the mounting bracket, through the engine block and finally from the block through the cable to the battery. Adding a cable from the case directly to the battery is a good idea though for a more direct route. When I do the upgrade on my other XJ I think I’ll add one there as well.
09-29-2018, 04:32 AM
Help! Replaced main cables, big 3, new battery, issues
. I am new to all this electrical stuff and am at a loss....
