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Battery Cable Questions

BIGSLVRXJ

NAXJA Forum User
Location
Des Moines, Iowa
1990 4.0. Replacing the battery cables right now, I got the old ones off and purchased the new ones. Question is when I was taking the negative cable off there was another wire coming from the starter onto that stud. What was that and does the negative cable go in front or behind it on the stud? Or does it matter?(I forgot when taking them off) Also it's dark now so I can't install them so can anyone tell me if a 48" negative cable and a 38" positive cable will be long enough. The guy said those were the oem lengths but just wanna make sure.
TIA
Collin
 
Well, it's dark and raining here so I'm not going out to look, but something sounds wrong in your description. The starter grounds through the engine -- the only wires going to the starter are positive.

I suggest you not connect anything tonight, and do a bit more research before you risk hooking things up backwards.
 
Not sure where the other wire was coming from I just know there were two wires on the stud that comes from the engine, that the negative cable attaches to. I just dont remember which one goes on the stud first. It probably doesnt matter though.
 
Eagles right, no neg. cables going to starter- the only negitive cables are from battery to body, battery to engine
the pos. ones go like this: alternator to junction box, junction box to battery, battery to starter

hope that helps!

- edit] just went to double check- the other wires that i have sharing the ground stud on the engine with the batter go into a harness- i broke that off when I changed my cables a while ago- DONT break that off- i lost all the gauges and went i pu it in gear it nearly drove through the garage door - also there is a cable that grounds from alternator to engine
 
Last edited:
RENIX Battery Wiring (like on my 87, 88, and 89...)

Positive terminal carries two wires - heavy (OEM 6 gage) to starter B+ terminal, lighter (OEM 10ga?) to starter relay, 3/8" ring lug. Power distribution happens from starter relay, and that post is shared with about six other leads. Starter line is solo at the bottom end.

Negative terminal can (legitamitely) carry up to three wires, depending upon previous owner - Chassis ground to engine block, on machined pad above distributor, chassis ground to sheetmetal (pretty much anywhere,) and alternator case ground (battery negative to threaded boss on rear of alternator case, used to eliminate possible floating ground on alternator.) Typically, there will only be the one ground lead to the engine block and all other grounds handled thru branch circuits and that stupid little braided thingy bolted down on the cylinder head (which I always replace with cable - that thing gets dirty and causes trouble...)

Any other questions? I also use 2/0 welder cable and silver-over-copper ring lugs for my new major wiring - I'm a firm believer in overkill...

5-90
 
I'll see what I can do tomorrow. Thanks all.
 
so i got an issue with a ground on my 87 mj. ill have power to everything when i turn the key 1/2 way. all everything works. then when i turn the key to ignition it goes click and everything shuts off. i have to get out and mess around with the negitive cable on the battery... whos post never fits the clamp on the cable... and then i hear electronics buzzing again. so it does the same thing again when i turn the key to ignition. i know its not the starter becasue i have gotten it to start randomly in my efforts of just jigling the neg cable. when a starters gone im sure it dosnt shut off all power after the click. so then we realized it wasnt the negitive connection to the battery, but where the neg cable grounds, which looked to be the block. so do i need to just tighten up a ground or do i have a worse problem? thanks.
 
Grounds can be very funky, and a bad grounding for the vehicle can create all sorts of weird problems. So the smart thing to do is too connect all the grounds just like they are OEM, make sure they're all there, clean and in good shape. There are usually several from the engine to the body. As well, there is usually a 2nd wire on the battery terminal to the body.

Generally, the negative battery cable, the large heavy cable should ground on the Engine Block as close as possible to the Starter Motor that will give the best current flow for the starter motor which flows so much current that a little bit of resistance from traveling thru the block and bolts to other parts of the engine could make a difference.

1st Choice would be to connect exactly like OEM.

but if your lost and not sure where the OEM connection was made

2nd Choice would be a good solid bolt directly to the engine block (make sure to scrape away any rust or paint on the flange surface where the electrical contact is made) as close to the starter motor as possible.

Keep in mind heat and potential shorting from chaffing/melting wires, you get a short in a battery cable, the car stalls immediately, won't restart and its even possible for the battery to explode.
 
awsome i love exploding batteries under my hood! but yeah im gonna try and keep with the OEM configuration. i guess i just have to go mess with it. thanks
 
My 88XJ has a dedicated ground to the starter. I believe it is add on. There are dedicated grounds all over including across the hood hinges installed from one of the previous owners.

I believe because of a sound system. I pulled 'monster cable' speaker wire from under the carpet when i 1st got this project.
 
well i messed with it today. looked over the motor and made sure everything looked like it was connected. i found the battery ground on the block and it was tight. i followed the smaller positive wire from the battery and it was connected pretty solid as well. but i still had the problem. i dont understand how by turning the key i get a click all the power shuts off. i went to go jiggle the neg cable again and noticed its rooted together with the positive cable through black bendy tubing to keep it all organized, and it moved with the negitive cable. so could the problem be with the positive connection?
 
and it cant be the starter becasue it did start once while i was messing around with it. so it has to be electrical
 
i had a similar starting problem with my old 92 dakota. it tuned out that as the engine tried to turn over, it shifted positions slightly and broke the connection on the negitive battery cable enough to not let it start. i would jiggle it a couple of times and eventualy i got it to start. make sure the connectors fit, if not change something to make it fit snuggly and the prob may go away

hth
stewie
 
Sounds like you have a battery that won't hold the load. If it just clicks and the lights dim. Use a jumper battery and if it starts everytime, it's the battery

But don't dimiss the starter because it started once. My 88 balks at starting about every fifth time, a whack with an axe handle to loosen the corrosion and it will then start.
 
stupidfast said:
so i got an issue with a ground on my 87 mj. ill have power to everything when i turn the key 1/2 way. all everything works. then when i turn the key to ignition it goes click and everything shuts off. i have to get out and mess around with the negitive cable on the battery... .

BTDT.

You need to clean the battery post and connector down to clean metal. If the clamp won't get tight, you need to replace it. I've replaced mine with good quality marine type connectors (have a post and wingnut) and redid the cables with ring terminals.
 
Make sure your battery is a GOOD name brand battery, as I nearly learned the hard way that cheapo bats are nothing but a ticking trouble time bomb.....when I bought my 90 XJ, the seller installed a cheapo battery, and I soon had issues with the jeep starting at all, even after I upgraded the cables to huge gauge welding wire....eventually I discovered that my CHEAP battery had a broken positive terminal, and I was going to montana in less than a week. Woulda really sucked if that POS died somewhere in the wilderness.......
 
yeah i should take out the soda can tab thats shimmed inbetween the post and the clamp and replace that... i went under the truck and followed both pos and neg battery cables and checked all their connection points and everything was tight. it looked like two wires were getting really close or another close to a hot part so i seperated them and it started up twice in a row. so i think i should just go in and make sure everything is seperate. but im pissed cuz thats gonna get put on hold cuz i melted the spark plug and the corner of my piston in my 05 YZ today and my trucks gonna have to get put off again
 
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