Slow battery drain. - PeachParts Mercedes-Benz Forum

libbybapa · #1 06-26-2006, 05:51 PM

Pardon me if this has been convered previously.

I seem to have a slow battery drain on my 82 300SD. I have found that the relay in the "A" position is always clicked on (removing negative battery cable causes it to click off) and remains consistently hot to the touch. I will see if I can decipher what that goes to and whether or not that is normal (doubtful). If anyone has any input it would be greatly apprciated. I'm off to decipher the wiring diagram and try to get this sorted.

This is my wife's car and she's already needed to get it jump started twice

. I don't feel like getting another car, so help is apprciated...

Andrew

Brian Carlton · #2 06-26-2006, 06:08 PM

Quote:

Originally Posted by libbybapa

I have found that the relay in the "A" position is always clicked on (removing negative battery cable causes it to click off) and remains consistently hot to the touch.

That relay will be engaged if the key switch is in the I, II, or III positions, or if the driver's door is open. If the driver's door is open, then the key switch position is irrelevant.

You only have an issue with this circuit if the relay closes with the key in the O position and the driver's door closed.

libbybapa · #3 06-26-2006, 06:29 PM

Yup, driver's door was open. After that relay, the only amp draw (with doors closed and key in pocket) was fuse 13. Well, the dash clock has never worked, but was still causing a floating amperage draw somewhere between .05 amp to .2. With the non-functioning clock unplugged there seems to be zero voltage draw. I'll recharge the battery (new) and see if she needs a jumpstart in a couple weeks...

Thanks for the help.

Andrew

Brian Carlton · #4 06-26-2006, 06:36 PM

Quote:

Originally Posted by libbybapa

Yup, driver's door was open. After that relay, the only amp draw (with doors closed and key in pocket) was fuse 13. Well, the dash clock has never worked, but was still causing a floating amperage draw somewhere between .05 amp to .2.

Definitely the problem.

When the clock fails, the amperage draw to the clock usually goes up for some reason. I had the same issue back with the W123. Draw was 200ma on a dead clock.

Anyone who has a clock that is not working.......do yourselves a favor........unplug it.