1995 E320 wagon; battery drains over night. (If battery is disconnected overnight, battery is strong next morning.) I disconnected the negative battery terminal, and put a test light in series. Light is bright, indicating significant current flow. I pulled every fuse in the engine room fuse box, just ahead of driver. The test light never went out! Is there another fuse box?

The car has no aftermarket gizmos hot wired in.

Side note:
The ASR light come on with the second start-up of the day, but does not seem to have any effect.
When the battery cable is connected/disconnected/ connected, there is a click click click sound from what I assume is the ABS pump, in the front/driver's side of the engine room (many steel pipes going into this unit). If I pull the two relays out of this unit, the click stops of course, but the test light still glows brightly, indicating current.


The test light I refer to is between the batt neg terminal and the disconnected neg batt cable.
Thanks for your thoughts.

Notorious W124 "Phantom Drainers"

1.Antenna
2.Trunk Light switch AND the "Flex" point at which the Trunk hinge impinges
on the Wiring Itself.
3.A bad diode in the Rectifier Bridge of the Alternator.

If it drains a healthy battery overnight it's a Big Drain (s).
I'm gonna throw out a WAG since I don't know the schematics of your chassis's
wiring diagram...It's an UnFused "Hot At All Times" user.

Invest in an inexpensive DMM from Sears or HF.
You need to know how bad the Amperage Drain is .

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'84 300SD sold
124.128

I had a battery killer once. We couldn't find the problem, until I went to the customers house, where the car was dead, and saw the brake lights on when I pulled up. The owner would shut off the car with the brakes on, and the car still in gear. Then, they would put it in park and release the brake pedal.

I ended up adjusting the brake light switch on this car.

It's time to disconnect things on the car... one at a time, until the light goes out, then troubleshoot what's out.

It can be a royal pain, but hopefully, it won't be a hard fix.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

isolate the alternator - it can be quite a big drain when one diode goes bad. the brake lamps in a MB dont work with the key out, the bits that do work are the interior lamps, headlamps, parking lamps, trunk lamp.

There are some models that have two fuses behind the fuse box panel - I dont know what they are for, but cannot hurt to check them.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

I only mentioned the brake light issue because in the case of my car, everything the ignition switch controlled had been monkeyed with... rather than just replaced the bad switch that was on the car.

My car was the KING of bad repairwork.

My alternator can be simply unplugged at the unit itself. Someone removed the little air duct and hose long ago.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

Im not saying you are wrong, I did suspect that something must have been done to make them work without the key in order for them to work like that.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Right. No offense taken here, but I'm just throwing things out for the OP. His car could be as mucked up as mine was!!!

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

My 124 had the master relay causing this. It also caused the ASR light to stay on.

by master relay - you mean the over voltage protection?

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Lots of good thoughts here.
The drain is indeed big, since it kills a good battery overnight, and has the test lamp glowing at half brilliancy.

Alternator diodes sound interesting. Can I easily isolate it?

OVP relay? Again, can I unplug it? I think it is behind the battery.

I don't see any lights on overnight.


The car in question is my daily driver, 1995 E320s, with 202k on the clock. I throw two kayaks on the roof, twice a week, keep the paddler in the boot, and generally enjoy the car.
Thanks again.

First thing to suspect is the OVP. My 124 gave me fits with dead battery issues. Rain water got into the relay from the cracked rain gutter above the battery & cover for the OVP. R2'd the OVP & made a raincoat for it with a plastic sandwich bag & a twist tie. That ended the problem. The other issue is a fuse in an unpopulated holder. Check your fuse chart & if is suppoda be empty don't put on in there. Many years ago with mine, I installed a fuse in a holder that was not normally populated with the intent to carry another spare fuse. Big mistake. Be patient, you'll find it! Let us know how ya made out.

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Edgar

This is what happened to mine. It was like a swamp in it.