Tracing Electrical Problem....

[Ripley Bryant]

Ok.. I'm getting frustrated here...

I have a short or drain somewhere that will drain my battery if it sits for 3 or more days.

I have been trying all day to figure out where it is with no luck.

Here's my attack so far... I have my multitester connected between my battery and the positive battery cable.

Registers 12v...

I have removed all fuses from the fuse panel and unplugged the wiring from the radio that the PO installed.

No Change, Registers 12v drain...

I have one by one unplugged and reconnected every plug in the engine bay... No change.

I have unplugged the dome/cargo light wiring... No change

I have removed a bunch of extraneous wiring the PO had to help clean things up a bit.

Under the dash, if it wasn't connected, I removed it..

Under the truck, I traced 3 wires, two for a plug the PO had for the canopy lights, removed those... No change.

Traced the wiring for a bed mounted gas tank/diverter valve, removed the wiring... no change.


At this point, I just need some guidance. Am I correct in thinking that with the ignition off, and the doors closed that my multimeter between the + side of the battery and the + battery cable should register 0v?

Any suggestions on how to proceed from here?

The only obvious thing I haven't checked is the wiring for the tow lights. There is an aftermarket (I think) bunch of wiring for this on the firewall, some of which I removed when removing disconnected wires and the 2 toggle switches the PO had under the dash. One was for the bed mounted gas tank, and the 2nd was connected to the trailer brake stuff...

Other than this drain/short, everything works fine.

[NeCrOmAnCeR]

You're approach of removing fuses etc.. is correct. However, with the positive cable disconected and the meter conected between the battery and cable it will many times measure battery voltage due to oil and other contaminants on the starter etc. I believe you are thinking of a current draw test. If you're meter can measure DC current, switch the meter to do so and connect it as before between the battery and cable. With everything off doors closed etc. I would expect the battery drain to be a few tens of milliamps (If you have a radio with a memory feature) or zero otherwise. Do the same thing you have before by removing fuses until you find the problem. I hope this helps,

[Blue Beard]

I had a similiar problem, went down the same lines.........

One major issue was the positive cable was grounding against the block behing the manifold.

Another thread indicated that the wires going down the drivers frame rail has wiring that sometimes goes bad....

[Ripley Bryant]

Necromancer,

Thanks...

I did measure the amperage and on the 30milliamp setting on my meter, it pegs the meter. On the 10Amp setting, it doesn't register.

Have since reconnected all the things I unplugged and installed all my fuses. Will resume the hunt next weekend. Will just disconnect the battery when it's parked for now.

[Ripley Bryant]

Blue Beard,

I was under there, tracing wiring for the canopy lights and the auxilliary tank wiring and removed that stuff. Didn't see anything obvious like melted wires/insulation, etc...

What exactly do you mean by the wires sometimes go bad in the driver's side framerail?

Thanks,

[Prerunner1982]

i have a similar problem, except instead of 3 days its 6hrs. i have dont everything except disconnect the alt. It appears to be going bad as well, so like yourself i disconnect the battery every night.

[Blue Beard]

The post mentioned the wires on the drivers rail rub where you can't see and creates a bare spot that creates short.....

[TROYLV]

try disconnecting the wires from the alt. sometimes diodes go bad and will alow small current to flow to ground. if this is the case the alt won't be long going totaly bad and draining the battery in about 5 minutes.

[Ripley Bryant]

Thanks Troy!

I'll give that a shot tonight.

[flip66]

Has seen were the alternator is week but not bad. If you test it will show 12 volts output but will only show 20 amps output when it should be at least 60 plus.