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Need electrical help!!

mitsumotors

NAXJA Forum User
Location
Winnipeg
My 91 xj, 4.0 AW4 will not start. about a month ago i couldn't start it or even get any power with the key turned. I found that alot of my battery wires and grounds were really corroded so i replaced all of them with new 2 guage wire. that fixed the problem. now after driving it for over a month it is doing the same thing again. when i turn the key on there is no power to any accecories or anything and when i try to crank it over there is nothing. I put a multimeter on the battery and for some reason its reading around 6 volts. any ideas?:worship:
 
well, if your batt is reading 6v, then its shot, but why? Is there a slow drain, physical damage, is it sealed (water level)?

As far as your grounds go, re-check them. I did the grounds on my buds grand c., and I missed one that was %60 of the problem (on the block). I then also inspected all electrical connections under the hood, relays, etc... I've never seen that much corrosion under the hood of an other wise rust free vehicle, but then again this is the same guy that runs 4 diff size tires on a 4wd, and changes his oil every 30k, or 2 years, which ever comes FIRST!!!
 
Charge your battery on with a battery charger (best) or jump Jeep with jumper cables from another vehicle to get it started. While running (jumper disconnected) test voltage again. If it checks 13.5 or so while running, charging system is good and battery is shot. Take it out and get it tested.

My first assumption would be that something loosened up with your wiring, but I'm sure you already checked all that stuff.
 
yeah, i checked some of the wiring that i replaced last time and it all seemed good. all the grounds are good and new. but doesn't it seem strange that even with 6V it doesn't try to start or power any of the accessories even a little? well actually out of evrything i checked, the headlights four way flashers, etc. the only thing that was getting some(very little though) power was the power seats? kinda strange.
 
it seems that both this time and the last time this happend it was after letting it sit for 3 or 4 days without starting. but the first time it wouldn't help to try and boost it because the poor battery cable connections that i have since replaced. i'll try boosting it tonight i guess and see if that helps. although to me, if it was an issue of the engine not being charge that was not allowing it to start the fact that it has 6V of charge right now and i still can't get it to try to start at all tells me its more than just lack of juice. but i don't know too much about electrical stuff so i could be wrong.
 
Put it on a charger, or jump it, and take it somewhere and have both battery and charging system tested. It will just take a few minutes, and you won't have to guess at what might be wrong.
 
It HAS to have all 12 volts to turn over. Most of the stuff under the hood won't even wake up and work under 10 volts, especially sensors, etc. No volts, no crank, no computer input, no start.

At 6 volts I suspect the battery has an internal short. Take it to a parts store, have them put it on their test/charger, and watch the results on the computer screen. If the battery is good, you might possibly have a small short that is draining the battery over a few days.

Once back with a good battery, hook it up with an ampmeter that will read 10 amp draw and see if it's getting drained. After that, you have to chase it down - pull the fuses one at a time to isolate the circuit, then look for cuts, frays, and damaged parts leaking current back to ground.

Volt/ohm meters with 10 amp scales are available for $20, service manuals with wiring diagrams $25. These are the primary tools for any mechanic today, not a socket set.
 
6 volts won't get it. And the usual sign of failure due to old age for my batteries has always been when it won't start after sitting a few days. It begins when it cranks slow after a week or so of sitting, but you drive it around a little and it starts up good until you leave it sit for a week again. Then gradually that time gets down to a few days. That means time for a new battery.
 
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