1993 850 Battery Drain

JeffHicks · Post by **JeffHicks** » 18 Feb 2014, 15:52

I'm trying to help a friend of a friend, who has a '93 850 GLT. Pretty nice car, in nice condition, with about 120k on it.

The problem is that the battery has a slow drain we cannot find. We've thoroughly poured over the car, looking for all the usual suspects. Nothing.

We disconnected the negative battery cable, and put a tester light between the cable and the battery post to check for continuity (if that makes sense). One by one, we pulled each fuse and relay, trying to find any direction. We found nothing - the light always stayed on. Dim, but on.

When I started pulling the connections of the radiator fan relay, the light went "almost" out. It grew extremely dim. The problem is we could not repeatedly replicate it. The light did not turn back on immediately when I plugged the wires back into the relay. After a few moments it might come back on, then the next time it might take a minute or two.

Questions:
1. Something is going on with that relay. But it is possible that it's just randomly sticking - causing it to neither be always on or always off?
2. Is that relay a common fail problem on this car?
3. Are there any other typical culprits for this random battery drain?
4. The continuity light stays "barely on." In daylight you can barely see that it's on. Is it possible that the pcm and/or digital clock draw just enough electricity to cause the light to be "barely on," or is it apt to be something else.

Any thoughts, ideas and opinions would be greatly appreciated!

xjflexer · Post by **xjflexer** » 18 Feb 2014, 15:57

It's not uncommon for the glove box door to warp slightly causing the glovebox light to not turn off. This was the cause of my draw a couple of years ago. I hope it's that simple for you.

Post by **erikv11** » 18 Feb 2014, 17:48

Try putting a multimeter in there instead of a test light: how many amps is it drawing? About 50 mA is typical, see if you are in that ballpark. If it is higher, do the fuse thing again and measure the changes in the amperage.

joe_pinehill · Post by **joe_pinehill** » 19 Feb 2014, 04:01

does it have an original or after market radio?

Post by **abscate** » 19 Feb 2014, 04:05

You need to move from the qualitative light test to a VOM test as noted above.

Bad grounds can also cause wierd current problems

JeffHicks · Post by **JeffHicks** » 20 Feb 2014, 08:22

Thanks for the replies and ideas, guys!

Her battery died again over night. In addition to using a multi-meter to get some more accurate readings, I'm going to take the battery in to see if it's okay. I suspect that it might have frozen solid, while dead, several weeks ago during an extreme cold snap.

Beyond that, I'm kind of grasping at straws. The OEM radio/cd player is removed, as is the glove box light. We've poured over this car several times, including systematically pulling fuses & relays to try to isolate the problem. We're getting to the end of possibilities. But we'll keep at it!

Thanks for the help!