Hello guys, as the says i have a parasitic battery draw that has forced me to set a remote battery kill-switch as an unsustainable measure to be able to use the car.
key points to consider:
-battery draw takes around a full day to discharge a the battery in summer
-Canadian winter, so yeah, cold.
-stupid kill-switch mechanism doesn’t withstand temperatures of -10C and lower.

I suspected it to be the car engine temperature sensor, but the sensor is funcional, although, i find it weird that the instruments displays a constant “+85C” but when i navigate with the arrows, and put the temps, the readings are correct. (Refer to pictures provided).

I have already done many fuse tests to try and find where the heck is this battery draw coming from, with no answer.
i might conduct another tests this weekend following a guide i found to see if i nail it this time.

Any idea or theory will help, thank you all in advance.

 

If you have power seats, try disconnecting the power seat control module for the passenger seat. This fixed my parasitic draw on my early 203.

 

Yes, what he said. If you look around here and/or on benzworld you will find a thread with instructions on how to install a relay
that will shut off power to the module (one relay per side) when you turn off the car.
Or replace the modules. #1 cause of parasitic draw.
Another one is the alarm module. Not enough to drain overnight but eventually the
backup battery inside shorts out and requires replacement or removal. It will blow the fuse that opens the doors.
Just went through that recently.
Also any scanner that reads Merc codes will typically tell you if there is a short somewhere.
read codes on each module.
It told me the alarm module was shorted.

 

Have you measured the current? It must be 20 mA after around 30 minutes of not touching the car.
+85 °C is the ambient sensor located in the front bumper on the right side, obviously wrong.

 

No power seats, still unplugged every connector from both seat modules, still a parasitic draw of .8A~.7A

 

Thanks, now i know where that temperature reading comes from.
draw is 0.8A~0.7A, as stated above on another reply, its not the seat control modules since i unplugged ever connector on both seats.

 

What I do: Open hood, trunk, drivers door. Walk away for 45 minutes. Take a multimeter on millivolts and measure the voltage at the fuses. If you see 0.1 mV or more there is too much current on the fuse.

 

So mb ennabled scanner provides no clues?

 

I just finished working on another early 203 with a parasitic draw. This car’s Overhead Control Panel was drawing about 90mA. The OCP gets its power from fuse 9 (25A) in the rear SAM (rear fusebox, located on the left side of the trunk/boot).

 

Did you mean the small ventilator inside? I should go into sleep mode after 20-30 minutes, if not it is damaged.

 

I’m not sure what you mean by ventilator, but this is the OCP:
http://www.micro-tronik.com/learning...control-panel/

When I disconnected the OCP, the current draw dipped to 20mA after 5 minutes, and remained there.

While it was connected, it wouldn’t go below 110mA, even after waiting 10 minutes.

 

Behind N70b1 is a small ventilator for the climate system, it is running for at least 20 minutes after you stop the engine and draws around 100 mA. You should hear some humming.