View Full Version : checking fuses to find a draw

07-11-02, 10:29 AM
I need somemore help guys.

When I pull a fuse end out and put my meter between the end of the fuse and the fuse holder I'm reading a negative 14 volts. I only checked 2 fuses and both read negative 14 volts. This isn't normal is it? I've never been any good with car's when it comes to wiring.
I do remember reading somewhere that the above method is the way to find out where your draw is, but don't know what I'm suppose to be reading.

I left my battery hooked up overnight ( which I learned along time ago not to do.) checked the battey this morning and read 10 volts. Jumped the car and after a few minutes it was up to 15 volts, so I know my charging system is okay.

Any guidance will be appreciated.


07-11-02, 11:03 AM
One more thing, after pulling one side of the first fuse (gauge fuse) my gauges were all still working.



Karl Snedeger
07-11-02, 01:49 PM
First of all, you probably had the meter's leads reversed and that is why you were reading a negative 14 volts. Second, if I am not mistaken the fuse marked gauges is for the lights on the gauges. I'll try and think of way to correctly explain the way to diagnose the draw on your system.

07-11-02, 02:58 PM
Thanks Karl,

Boy do I feel stupid:hb , I'm an electricain by trade. In my defence I work with AC not DC.

Could you tell me if testing at the fuse would show me which system is drawing to much and how it does this? This assuming of course that I put the leads to the correct post:L

Thanks for the help,


Karl Snedeger
07-11-02, 03:07 PM
I'm trying to think about yourproblem and all I come up with is it has to be something that is always on-dome light circuit, starter circuit, brake light circuit etc. I can't remember how to test I'll keep thinking and asking around.

07-11-02, 03:54 PM
Does the original alarm system draw power? I read on another post that someone had the plug on their alternator (one red wire and one brown wire) plugged in backwards, and it caused a drain. However, I would not go flipping this plug around without furthur exploration.

07-11-02, 04:12 PM
No alarm system here.

I know I'll be able to figure this out.

I just thought maybe someone had done this type of testing and would be able to tell me if something were drawing down my battery how I'd be able to isolate it to which system, using the afore mentioned method.

Should the car be running or not.
Should I be reading at the battery or at the fuses.


07-11-02, 04:33 PM
Disconnect your negative battery cable and place either a test light or your meter (on milliamps scale) between the battery terminal and the cable end; if anything is drawing current, you'll see the light (or meter indication). Pull the fuses one at a time - when the light goes out (or the meter zeroes), you've found the circuit with the draw. Then look at the wiring diagram and see what items that fuse feeds, and start checking each item for a short. If none of the fuses causes the light to go out, it's in a battery-fed circuit that's not fused (like a shorted diode in the alternator).

07-11-02, 05:51 PM

You are the man.

Thanks alot, I'll be checking it out some tonight.