Battery drain issue...oh joy..

[ziff73]

Okay, I have the small under seat set up and if I don't keep the battery hooked up to a tender, she drains pretty quickly. Before I start tearing everything apart:

A. I noticed that when I touch the ground back to the battery, I hear a click and the fuel gauge pops to life...is that normal? Is that draining the battery?

B. what should I look for, in particular, that would be causing the problem.

some background:

I have a carter fuel pump (I know, I wanted mechanical, but had to use a previously injected head) No wipers hooked up, no horn yet, and no radio. There aren't too many things on this car to begin with, so hopefully I can find it quickly.

Electrical work is my Kryptonite...I'll do it to save a kid from a burning building, but not for fun...:-)

Thanks!

Stephen

[baller908790]

I used this video to find my electrical gremlin.

Mine was the dome light was on but the bulb burned out.

Basically you hook up a anmeter to your

battery and unplug fuses

to see when the meter drops. The video

will explain it a lot better though.

[Hans]

You can use fuse pulling method to home in on circuit, but seems to me fuel gauge should be off when key is turned off and removed. On 02, there should be virtually no draw - maybe with modern radio. Not like new cars. So maybe ignition switch or some misconnected wires at fuse box??

[esty]

disconnect the positive battery cable...put a test light between it and the positive post....if you have a drain, the test light will light.....pull fuses one at a time until light goes out...that tells you which circuit is the culprit

[ziff73]

Awesome. Thanks everybody. Looks like I have my rainy weekend work all lined up!

Does anyone know for sure about the fuel gauge reading all the time? Does anyone else's do that? Thanks

Stephen

[BillWilliams]

You fuel pump should be wired to "switched" power not "constant" power.

[ziff73]

Fuel pump is good on switched power, but I just looked into the fuel gauge issue and found that it does seem to be 'turning on' when the battery is connected and when I pull the wire from the sending unit on the gas tank, it clicks back down....obviously... so my question is, why would that be constantly hot? Did I somehow attach constant power to it instead of switched, like the rest of the dash?

Man, give me an engine to rebuild any day of the week...electrical gremlins...grrr. Thanks for the help everyone.

[ndog]

yes.... you found it. someone hooked unswitched power to your gauge,or........ a connection to the gauge and another unswitched source decided to party together.

[OriginalOwner]

+1 ndog.

I would imagine the fuel gauge is switched, don't need it "on" when you can't see it.

Cheers,

Carl

[ziff73]

Cool. Does it make sense that maybe I put a wire in the wrong place on the back of the ignition switch when I reassembled the car? Well, that wasn't too bad...now to fix it!..;-)

Thanks again

Stephen

[Hans]

yes that makes sense. One of those terminals is hot always. Or switch is getting flakey. Or wires got mixed at fuse box: some fuses are hot, some switched power.

[allbim]

With everything off, pull one fuse at a time and put a test-light across the terminals. If the light comes on, you found the offending circuit.

If you don't find it that way, then something is incorrectly wired into an un-fused circuit.

[Hans]

Possibly un-fused, but definitely hot always (i.e., not on with ignition). You mentioned working on the ignition switch: I'd check your connections there. There is one "always hot" terminal that you may have used by accident. How many fuses do you have? On 12 fuse box, wire from switch to fuse that appears to feed gauge comes off switch.

[ziff73]

I'll have to slowly poke around in there, as the PO had switched from 6 fuse to 12 fuse at some point and probably didn't adhere to a specific BMW diagram... Should be a nice learning experience...;-)

Stephen

[Hans]

As you said: oh boy. I'd be starting there. Try the fuse removing process to confirm which one controls the fuel gauge. If that is the correct fuse (11 or 12 I believe) then check switch to see if wire form switch is on switched or always hot terminal.