Battery drain - fog lights to blame?
 

Im trying to track down a drain on my battery that leaves me with a dead battery if the car sits for a couple days. I just replaced the bulbs for the fog lights on my 83 SC a couple days before this started happening, and that is the only thing I can think of that might be a source of the problem. Anyone know of any issues associated with fog lights on an SC that are known to cause any similar issues?

Take off the fuse but i dont think that your problem.Check your battery.

Right - get the battery load tested first. If that's not it, then:

Make sure your interior light is not on - a three-way rocker switch with off/on/on-when-door-is-open. It's easy to knock the switch into always-on, and it's easy to not notice.

if it's not that, disconnect the battery ground cable and connect an ammeter, then pull fuses one by one until you see the drain go away.

The other common culprit is a malfunctioning aftermarket alarm or stereo.

Light under the dash was the culprit once for me....

trunk light switch sometimes does not go off

Thanks. I'll take a look at each of these. It just seemed too coincidental that I never had any electrical issues until 2 days after replacing the fog light bulbs.

Those probably pull between 0.5 and 1 amp.

If you don't have a MM, you can cheat by pulling off the negative battery cable. When you touch it back onto the terminal you will hear a micro sizzle as the two try to weld themselves together. Pull the fuses one by one and wait for the noise to stop.

This assumes that the battery is fine and gasoline is not pooled up in the battery tray.

on mine it was the FENSTERHABER relay sticking, I foung the issue using the same Bob K trick,m but I actually heard the faint relay click.

the Fensterhaber/window relay can remain activated/armed (and draining current) if the door switches that trigger the interior light fail -- does the OP's interior light come on when either/both doors are opened?

Darrin,
So if the jamb switch does not turn on the lights, then the FH relay stays activated , draining juice, waiting for the light to turn on signifying the door has opened and cutting power to the windows ....right?

That system is so sketchy, its failure mode is almost invisible to the operator....then you drain the battery.

Expand on this a bit, please.

bingo!

I believe the relay is triggered by either door opening. So, if the passenger door jamb switch still works, opening the passenger door should trigger the relay and cut power to the windows/eliminate the parasitic drain

This thread was timely for me - I *thought* I had identified the battery drain issue in my just-acquired '72 just a few days ago - the aftermarket stereo is not wired to a switched circuit, it's always hot. And, every time the battery is disconnected, it turns on when power is restored. So - I had assumed that I was just leaving the thing on by accident, and made it a point to verify it was off when I shut the car off. I should just take it out - the M&K is so loud, it seems silly to even have a radio in the car. But - this very morning - I go out to start the car and the battery is drawn down again, and I look and the stereo is definitely off.

Tonight I started over - I tried the ammeter as I thought I so cleverly suggested above, but found out that my digital multimeter is broken as an ammeter (it is 20 years old and kind of flaky - makes me wish I had kept my old analog meter) . Anyway, that didn't work, and the individual fuses didn't seem to spark as I pulled them. So I checked my frunk and interior lights which seemed to be operating correctly. On a whim, I shut off the lights in the garage to make it completely dark - and voila - there it was - the engine compartment light was glowing through the grille. The cover was rotated mostly shut, but not quite, so it has been on constantly. Doh!

Thonk about it for a minute. For the fog light bulbs to be draining the battery, they would have to be glowing. That's what they do when electical current runs through them. Are the fog lights on? I think not.

Onward, to more likely culprits...

JR

jdbunda, your engine compartment light should be connected to the sidelight circuit so it can only come on with the sidelights/headlights and not have a continuously live 12v supply.

Cheers, Neil

OP's car is an 83. The fenster-miester relay started in 1984.

Not sure what a Fensterhaber is but most cars have a Fensterheber. :)

german for "window regulator," right?

Bob -- so prior to 1984, electric windows would stop operating once the ignition is turned off?

Well on mine at least. I hope something is wrong that I can fix but I don't think so. I may well have a relay that is up in deep near the frunk "firewall" by the flasher relay but from what I have experienced I do not have the window courtesy function post shut down. Windows be dead when key is off.

The juice draw makes perfect sense. Relay is energized just waiting for you to close the window but it does not know you opened the door.

I found ganun's thread on his relay and loaded the 944 prefix number into PP's search engine. That relay is for 84 an onward.