Voltage Leak
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Junior User
Joined: Jul 2009
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Voltage Leak
Hey Guys,
I'm looking for some help on tracing a voltage leak. I have new batteries and am having a problem with them getting weak for starting when the truck sits for a couple of days. Once in a while even overnight. They seem to be charging just fine because they will be real strong through out the day while using the truck. I've read some articles on how to trace the leak but wonder if it is a different procedure with two batteries. Any and all help will be appreciated.
Thanks,
TJ
I'm looking for some help on tracing a voltage leak. I have new batteries and am having a problem with them getting weak for starting when the truck sits for a couple of days. Once in a while even overnight. They seem to be charging just fine because they will be real strong through out the day while using the truck. I've read some articles on how to trace the leak but wonder if it is a different procedure with two batteries. Any and all help will be appreciated.
Thanks,
TJ
Elder User
Joined: Feb 2005
Posts: 896
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From: Chattahoochee Hills, Ga.
Best way is to disconnect a ground cable, put a good digital meter in line between ground and the disconnected cable, measure the voltage on a low scale then get a buddy to pull one fuse at a time till you see the voltage go back to zero. It takes some time and some help but you can find it and at least know which circuit your problem is in. From there, visual checks for chaffed wires, faulty switches etc. Good luck, I found mine this way and you can too. My wife helped me and is much more organized than I am so she was GOOD help.
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Junior User
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2 alternators
I have 2 alternators. Is it normal to have 2 alternators because there are two batteries? Bob do I just remove one of the batteries negative cables to put the multimeter in line?
Posting Guru
Joined: Apr 2009
Posts: 2,447
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From: Northern Idaho
If he sets it in the voltage position won't it still give him a voltage reading with everything off?
You'll need to disconnect both batteries to ensure that the battery you are testing from is the only place that the current can go to. You don't want it to try and skip past where you are testing from and go to another source.
You'll need to disconnect both batteries to ensure that the battery you are testing from is the only place that the current can go to. You don't want it to try and skip past where you are testing from and go to another source.
Freshman User
Joined: Nov 2006
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Some have dual alternators, some just have one. When you get up in the morning feel both of them. If one of them is warm I would bet that's your problem. If they are both cold, time to start pulling fuses. When we figure out which fuse has the draw, we can tell you whats wrong. Do you have a multimeter?
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Freshman User
Joined: Nov 2006
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I think he needs to be reading amps not volts. But I could be wrong, it has been a couple years since I had problems with mine.
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Posting Guru
Joined: Apr 2009
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From: Northern Idaho
I agree and was reluctant to say anything but the problem is that if the source is pulling more then 10amps most typical off the shelf voltmeters will blow a fuse at 10amps.
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Junior User
Joined: Jul 2009
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i will see whats up on monday morning.
gonna check it out Monday morning. I have a decent multimeter. At this point I'm actually hoping one of the alternators is warm. Nice and easy. But we'll see. Thankd for the help so far. I wont be able to get to it until Monday but I will keep everyone informed.
Posting Guru
Joined: Apr 2009
Posts: 2,447
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From: Northern Idaho
You do realize that you have to check the alternator before driving the truck, you know, when it's been sitting all night and not right after driving it??? 
Messing with ya!!
Anyhow, please do get back to us and have a great weekend!
Messing with ya!!
Anyhow, please do get back to us and have a great weekend!
Cargo Master
Joined: Jan 2001
Posts: 2,726
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From: Slatington, PA
You wanna set the meter to amps and start with the 10amp setting. Unhook both of the ground cables and connect your meter between one of the negative cables and the batery (ground cable to positive on meter, negative on meter to battery). You should get a low reading. If its drawing more then an amp after a few minutes (IIRC, the draw right after shutdown is higher for a little while), start pulling fuses until you find the one that makes the reading drop, thats the one causing the battery drain.
Elder User
Joined: Feb 2005
Posts: 896
Likes: 1
From: Chattahoochee Hills, Ga.
Trevor is right, amps and both negative cables. Might even have to look at milliamps to see it. I was running out the door last night and didn't give you the attention you needed. Sorry about that ! Thanks to the other guys that jumped in. My problem was in the facotry radio, some component failed and was drawing current all the time.
Cargo Master
Joined: Jan 2001
Posts: 2,726
Likes: 5
From: Slatington, PA
I mentioned using the amps setting first cause I think some components pull quite a bit for a minute or two before going below one amp. Whenever testing an unknown voltage or amp reading on a meter, its always best to start at the highest range and work your way down.