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99 F250 Electrical Issues

13205 Views 9 Replies 5 Participants Last post by  ChadHowerton
So I have a 1999 Ford F250 Superduty with 2 batteries. It has the 7.3 of course. I'm having an electrical issue. I have 2 brand new batteries and a brand new alternator but I keep walking out to dead batteries. About a week ago I was driving and I heard a loud "pop" that sounded like it came from down under the dash but I couldn't find anything. After that I hadn't notice anything but then the truck started hesitating starting a little and then this morning it was dead. I have a new alternator and 2 new batteries so i'm confused. Nothing was left on, all lights were off. When I came back to the truck this afternoon there was a clicking coming from the fuse box underneath the dash. I know it had been previously replaced. So i'm basically stuck, I have no idea what it could be.
Any help would be greatly appreciated!
Gahhh seems like i'm fixing or repairing daily
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Sounds like you have what's called a Parasitic Draw, something is using too much electricity when the truck is off. These things can be tough to find, and drive you crazy! :wink[3]:

Yours seems to be consistent at least, be glad of that, the internment ones will kill ya...

It's detective work really, but you need to prepare to have your batteries dead while doing it (for important times pull Both (+) cables when it sits.)

You can use a mulit-meter inline with a battery terminal in the Amps position to see how much current is being drawn (do this with with one battery disconnected to know the total amount). Shouldn't be much after things "settle-down" as the truck sits (takes awhile for all the electronics to shut down - up to 1/2hr)

You could also start by just taking 1/2 the fuses out of the fusebox and see if that stops it. If not, replace them and take the other 1/2. Then put some back until you narrow down the circuit that has the draw. It's a process.....
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No, you're always going to have some draw (the PCM & GEM, radio, etc)

I thought, by the way you were talking, that it killed the batteries overnight? You think a full charge will last a "couple of weeks"?

So that's a different thing.... Yes and air pump coming on, because of a leak somewhere, is the kind of thing that could do that. Put a sw on the feed so you can manually control when it runs. Don't let it come on unless the truck is running maybe.
Again, putting a little bulb between the battery terminal and the cable end (I'm assuming that's what the "bag draw wire" is) is going to light-up for you, it's supposed to...

As for the POP, I guess maybe but usually anything that is electrical and makes a noise like that should be noticeably damaged.

If it IS an overnight thing, put on your "detective hat" and start testing by pulling fuses ;)
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