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Electrical problem. Help please

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Electrical problem. Help please
J

JanMast

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Vehicle(s)
1985 Jeep CJ7
I have an 85 CJ7 . I drove home from work and about to park in my driveway when i stalled the engine. It wouldnt start, it wouldnt even attempt to crank over. Even the lights wouldnt turn on. I had to push the jeep into its parking space.

I pulled the cables off the battery and checked it with a multimeter. I dont remember teh reading but it was below 12 VDC. I then reconnected the battery cables and jumped the jeep. I read 14 VDC across the posts when it was running. I believe that means that the alternator is doing its job. I bought a new battery. The jeep started with teh new battery in it. But the next morning it would start again. I was able to jump it, but again after an hour it wont start.

I believe this to mean that i have a load somewhere in my electrical system that is draining the battery. I have no idea how to troubleshoot this. Do i start pulling all the extra cables off the battery terminals and reconnect one at a time? And guidance would be appreciated. Thanks!
 
do you make a spark when you pull the battery terminal off?? Did you have the battery tested??:cool:
 
It did spark when i installed the new battery. I have not had it tested.

I havent followed all the cables that come off the terminals, but i did trace out a few. One was for the amp/radio. The other was for the winch.
 
as you suggested yourself,attach the wires one at a time to see which one sparks..not guaranteed but this might lead you in the right direction..leave the one that sparks disconnected overnight or whenever you are going to let it sit for a while and see what it does
 
Smart money is on the radio, if the winch were on you would know it. It is on or off, not a lot of grey area on that. Even if you find the power drain have the battery checked.:D
 
So I have had the same problem with my 1985 CJ7 . It would start fine then one day nothing. Then after setting would start fine for a while again. The time in between could be weeks. The other problem i would have at the same time was that sometimes the radio, lights would work, then other times not. This could be a long on going issues, (it has been for me) but here is what I have done.

1st. Get the battery tested, cause if its dead then none of this will apply. My battery was over 90% good according to two different parts stores bench test on load. So it was not getting drained by anything.

2. Check for corrosion on the battery cables at all ends, even the ground. (Remember a lot of issues can be traced back to a bad ground). I ended up replacing all of mine. After i did this i didn't have any this problems for a long time. Like months. Then out of the blue one day, she wouldn't start. Had no electrical power. After trying to jump it, still nothing.

3. So now i have replaced my starter solenoid. The one up on the passenger side fender. This was done about a week ago. But like the battery cables, I'm hoping nothing comes up after a few months

Hopes this helps a little

Scott P

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Hi,

Does your multimeter have a current setting for measuring amps? If so, this would be the best way to determine what load is on your system. Then you can pull fuses or extra wires until you find the source.

The tricky part of this that the meter must be in series with the battery cable. This is fine for small loads, BUT you can't hit the starter ! This would fry the meter. It will typically only handle about 10 amps.

John
 
Scott P. Thanks for the reply. I was hoping that someone else had this happen to them as well. I appreciate you sharing.

My meter can read amps as well, Fluke 77 BN, i will have to see what range its rated for though.

Also i have been meaning to ask... is there a fuse box somewhere in this Jeep? lol i have searched high and low and all i see is a bunch of inline fuses...

Thanks all for the replies! I will keep you updated on my troubleshooting steps and results.
 
JanMast said:
Also i have been meaning to ask... is there a fuse box somewhere in this Jeep? lol i have searched high and low and all i see is a bunch of inline fuses...
Click to expand...
You will find your fuse block under the dash on the driver side.
 
Just a little info. Just because the system reads 14v+ while idling does not indicate a good alternator. Your alternator could be producing tons of volts but no amperage. This would cause your battery to drop below a 12v charge while driving and cause it to not recharge from the alternator after jumping. From your description it sounds like you have a parasitic draw that might be killing the battery when it sits. However unless your radio is wired incorrectly the memory draw on it should take a few weeks to kill your battery the same if you have a factory clock.

I'd take your jeep down to the auto parts store and have them test the alternator's output to rule it out, they have a tool that can test it in the vehicle while the truck idles.
 
Well hell. To make a long story short, i installed a new battery. Then i removed all the extras and only connected the black and red cables. It wont turn over. It tried the first few times. Now it wont even chug.

So i tried jumping it. Nothing. Nada. Wont even try to turn over.

I am completely at a loss. Why would it not start this time when jumped, when it started a week ago when i jumped it.

I am completely at a loss. Should i just start replacing parts? Where would i start? Starter? SOlenoid? ALternator? I might be in over my head here. This jeep is making me question my cognitive abilities. lol Did i miss something i should have done? ANy further ideas or suggestions? Thanks in advance1
 
Ok, with radio and winch wires lifted your getting nothing. Battery voltage is still above 12 vdc and alternator test fine. I have been there before:D. I think we all have but anyways ,double check your solenoid, is your negative still grounded and not loose? I havent noticed where anyone mentioned the switch but stranger things happen right?

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I will check the solenoid ground. That's on the passenger side fender right? And what switch would you be referring to? Thanks!
 
Yes, the solenoid is on the passenger side fender. The ignition switch is what I was referring to.. Im not tech savvy enough to do so post the thread for you, but their in the electrical sections of this forum. These thread is what I went by when mine became problematic. Mine actually came with two extra starter solenoids when I bought it. First one was bad and I mis wired the 2nd one the first go around :D. Basically, I replaced the alternator 3 times and then replaced my battery with a optima, new battery cables and post clamps… no issues since. Good luck.

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JanMast said:
I will check the solenoid ground. That's on the passenger side fender right? And what switch would you be referring to? Thanks!
Click to expand...

The solenoid grounds itself out on the fender. Some guys like me add an additional ground wire to make a better circuit. I would suggest first checking to see if you are even getting 12v to the starter when you turn the key. From there check the relay, then the fusible links, wiring, and ignition key.
 
Torxhead said:
The solenoid grounds itself out on the fender. Some guys like me add an additional ground wire to make a better circuit. I would suggest first checking to see if you are even getting 12v to the starter when you turn the key. From there check the relay, then the fusible links, wiring, and ignition key.
Click to expand...

12V to starter, or 12V to solenoid coil?:cool:
 
For whatever it's worth I'd replace battery cables. Why would I do that? Because for something that never goes bad I've had one in two separate vehicles somehow go bad and drove me NUTS figuring out the issue and after I'd replaced everything else it was all that was left.

They're cheap and once your done you can scratch them off the list.



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Well I replaced the battery cables today, nothing. I will have to get help to see if I am getting 12V to teh starter or not.
 
JanMast said:
Well I replaced the battery cables today, nothing. I will have to get help to see if I am getting 12V to teh starter or not.
Click to expand...


Well I know it sounded silly, but you have new ones now. I'm sorry it didn't help.

Now back to the tracing. Need to verify the volts are where they belong.


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