Mystery Electrical Drain?

[ohecht]

I am finishing up acquiring and installing the last of the small, hard-to-get parts from when my driver's side CV joint let go and took out the throttle linkage, brake vacuum line, and CHT temp snesor lines, and I now have a drain on the electrical system I can't trace.

The battery had been drained twice completely (as in absolutely 0 charge) in just a week or two of sitting, which it never does. It is (was) a healthy Optima battery.

When the damage first happened, I noticed the tail lights were on without the switch, so I pulled the fuses, thinking it was a damaged part grounding the circuit somewhere under the car. Now that most of the parts are replaced and cleaned up, the tail lights work fine and are not on without the switch, but the car is still loosing current somewhere..

Does anyone have any ideas on how this could happen, which circuit it could be given the original damage, or how to determine where the load is coming from using a multi-meter?

Thanks in advance,

Olivier

[POKDUB]

My suggested means of isolating. Recharge the battery. Check that no wiring around fuse box is warm/hot, signifying hi current ampage. If all seems ok, I suggest you use the multimeter DC current option, on hi amp setting, to begin with. Place in line with each fuse (not across), and you should see which circuit at least is drawing major current.

If are a bit braver, remove each fuse and put meter across terminals, again make sure it is on hi current setting.

Dont turn on ignition at an point. Good luck.

[Icemaster]

Last time I had this happen (4 or 5 times last winter...) it ended up being the pin switch for the doors.

With the key out, open and close the driver door, then try the power window switch if you got it. Tell tale sign that the contacts need to be cleaned or pin switch replaced.

[cmonref]

POKDUB is on the right track. Use a multimeter than can read down to less than 5 ma. Using a higher range, check each circuit for a current, by placing the multimeter INTO the circuit, not across the circuit. When you get an indication that a particular circuit has a leak, switch to a lower range on the multimeter and read it again.

I found 2 ma in the clock and radio circuits. Those are OK. Found 150 ma draining thru the alternator, which was killing my battery over a few days.

Start at the battery--disconnect the + terminal. Test for a drain between the post and the disconnected terminal.

If you found a drain, disconnect all of the wires from the disconnected terminal, and test each circuit individually.

If the starter/alternator circuit is the problem, disconnect the large wires at the starter. REconnect the battery + terminal. Put the multimeter in the circuit between the disconnected wires at the starter (you are effectively taking the starter out of the circuit). If the drain is still present, remove the alternator and the B+ wire, and test across the disconnected wire and the B+ terminal. If still draining, the alternator is the problem.

Back to the battery: if the drain traced to the fuse box on the fender, reconnect the batterh. Sequentially remove each fuse individually and test across that fuse's terminals until you find the electrical drain. Use the high range on the multimeter first, then switch to a lower range if you get an twitch on the meter.

Good luck.

[ohecht]

Thanks everyone, I will start this tedious process as soon as I can...doesn't sound like fun at all!

Since I don't believe in coincidences and this started when the driver's side axle wreaked its havoc under the car, any ideas on what circuits are vulnerable? The problem had to have occurred at the same time, especially since the tail lights mysteriously lit up on their own.

I have so much aftermarket wiring going through the tunnel near the throttle linkage that got tweaked, that it could certainly be something in there...

Thanks again,

Olivier

[ohecht]

The good news is I found the problem before having to go through such a complicated process.

The bad news is I'm an idiot.

Turns out that the mystery drain was the glove box light, since the door was just barely open (not latched all the way).

Related to the CV joint incident since I opened the box when I called for a tow, but not mechanically related.

I never noticed since the battery was already drained before I saw the car in the dark...I just trickle charged the battery to start trouble shooting, and the light was obvious in the pre-dawn darkness.

Thanks again for all the advice, and I am glad to have one less item on my list.

Olivier

[POKDUB]

Glad to hear it was this simple.

You would not be the first, nor last, to tear something apart and find the problem staring you in the face.

Have the teeshirt.