Parasitic draw - PeachParts Mercedes-Benz Forum

Louis M · #1 05-02-2006, 09:11 PM

At least that's what i got it down to. If i pull the fuse that the clock is on the battery don't drain, what else is on that circuit i don't know cause i'm not home right now but the clock doesn't work so i would like to start by disconnecting the clock 1st and go from there.But how in heck do you do get back there and disconnect it ? cause there's no way i'm gonna start pulling and tearing when i don't know what i'm doing. If i hook a test light up to check for draw the light won't come on that's why i think it's parastic.I'm scared stiff to take it to a shop when i don't know who i'm dealing with so i fiqured i'd start here to see what you guys have to say 1st. It's an 86 with 140 klicks on it

ericdee · #2 05-02-2006, 09:58 PM

Here this worked for me.

http://www.diymbrepair.com/easley/clock.htm

tecqboy · #3 05-02-2006, 10:04 PM

May I assume, sir, that your battery is going dead for no apparent reason? The clock (10 ma drain ) will not run down a good battery for months. So, it's not the clock. Forget the clock. More likely than any other cause, I'd suspect the battery itself. Even if it measures 13.6 volts and turns over the engine, it may have developed an internal short. As batteries age, conductive material drops off the plates and settles to the bottom of the case. When it gets deep enough, the material shorts out the plates along the bottom. It's not a dead short, but rather a low resistance short. I've seen this happen on relatively "young" batteries, as rough physical service can aggrivate the condition. The check for this is to just dis-connect the battery from the car and find out if it goes dead on it's own in a few days time or less.

Louis M · #4 05-02-2006, 10:18 PM

Thanks Eric, i bumbed into that post but don't understand how to take it out, but when i get home i'll have a look. Although the instructions are very good getting it completly out i what i'm missing. Thanks for the fast reply. Louis

Louis M · #5 05-02-2006, 10:36 PM

Boy answers come in fast around here wow. OK -if i charge the battery right up in about 3 days she's dead,if i charge it up again with the fuse out that the clock is on and the radio and what ever else, no draw what so ever -starts fine after a long period of time -weeks- so when i took the battery out last fall put it in the basement on a piece of wood till this week she fired right up so i'm sure the draw is on that circuit but where is it what i'm after. Proccess of ilimination. But i will try another battery as you said -so now what do you think? When i bought the car and went to pick it up the guy hooked up the battery and that made me wonder what the heck i mabye was in for.Louis

Strife · #6 05-03-2006, 01:15 AM

The manual says the fuse is for:

Alarm
Antenna
Clock
Radio
Courtesy Lamps
Trunk Lamp
Turn/Hazard Lamps
Warning System

My car had the trunk lamp removed; I wonder if this was due to this problem.
Are you sure that it goes out (if you have one). Because you probably can't fit in the trunk, and there are probably laws against paying a kid to do it, put the trunk lid down, wait 15 minutes, lift the lid and see if the bulb/assy is warm.

Failing that, it is possible that the capacitors in the clock can be leaky and partially shorted, considerably raising the current draw even if the clock still works.

The clock has only one wire going to it, a flying lead from inside the instrument cluster area of the dash, very easy to remove, but it's a bi$@# to get to without removing the instrument cluster. You have to be careful with it because it is hot at all times that the battery is connected, and mine has broken plastic insulation.

I have instructions on instrument cluster removal on my website (they are pretty good, but use at your own risk).

I have some other ideas but they will be more difficult to test.

coleyjf · #7 05-03-2006, 06:34 AM

Hi Louis

I've had similar problems and found it was my Alarm Immobiliser and Tracker systems which were draining the battery (all depends on which alarm etc has been fitted to the car - mine's a UK system.

Initialy I thought it was a faulty battery but after swaping the battery - no improvement - dead in a week so after measuring the drain from the fuses with everything switched off I found it was the alarm/clock/etc fuse so switching off the alarm with the key - presto - lower drain and no dead battery!

Cheers

Jim

t walgamuth · #8 05-03-2006, 07:39 AM

on my sec the trunk light was not shutting off and was draining it if it sat for a while. we took out the bulb and fixed the problem.

tom w

tecqboy · #9 05-03-2006, 12:18 PM

Ah yes, I had forgoten about the trunk lamp. The switch and associated vacuum lock check valve have a reputation for failure. In some instances, the trunk will actually unlatch just enough to activate the lamp. You won't see the lamp on, but you'll notice this because the trunk is not latched shut.

Louis M · #10 05-03-2006, 08:14 PM

Ok good now we got action. I'll try all that stuff which all makes sense this week end when i get home. I can peel the dash off pretty quik on Chev's and Ford's but playing around with this stuff is a whole different ball game. Thanks -i'll get back when i have a chance---Louis ---alberta