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Battery Draining Overnight - CAN BUS never sleeps SL500 2013
Hello everyone, I'm currently losing my mind over this issue.
For a month now I I've been trying to solve this issue. All started with a dead battery one morning. Charged it up and everything looked. Car was working again. Next day, same issue.
Symptoms:
- Battery drains at a rate of 3.3 Amps. Even after an hour of locking the car.
- Scan tool shows only one issue: B1002
- (Maybe something) Position lights flash. When I turn the key to ACC (Accessory), turn on the lights, then turn off the key. The lights start flashing. I don't know if that is supposed to be like that.
- Temperature on the dashboard is wrong (+85.0C all the time)
What have I done:
- Changed the battery for a new one.
- Verified that the charging system works properly.
- Unplugged one by one every fuse of all 3 fuse boxes with amp meter hooked up.
- Unplugged the COMAND and amplifier.
- Verified / unhooked the Alarm/Siren (No battery leak found)
What I could find so far:
- CAN bus never goes to sleep. Specifically the brown / brown red network. Green white shows no activity after a few minutes.
- CD unit makes noise every few minutes.
- Fan behind the dashboard also starts and stops continuously.
I ran out of ideas and forum threads to read.
I would really appreciate if you could point me in a new direction that may help me find the cause.
hi there, what are you referring to with 'position lights'?
If when you lock the car the indicators are flashing different, it could be an indication of a faulty alarm siren. I had this found I had moisture inside.
Let me know if you need a video as I filmed how to access the alarm and reposition.
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Nasty business, your frustration is justified...
Hopefully someone more knowledgeable than me will chime in. What I can give you is a list of components that you cannot disconnect by pulling plug in fuses. These components are protected by electronic fuses.
By the way, in stead of pulling the plastic fuses one can measure the drop of voltage between their poles (if you can get to them with a thin probe), indicating the current running through them. There's tables for that.
hi there, what are you referring to with 'position lights'?
If when you lock the car the indicators are flashing different, it could be an indication of a faulty alarm siren. I had this found I had moisture inside.
Let me know if you need a video as I filmed how to access the alarm and reposition.
Thank you for your reply, I attached a short video of the flashing lights.
Regarding the alarm, I've managed to get it out already, thank you.
Nasty business, your frustration is justified... Hopefully someone more knowledgeable than me will chime in. What I can give you is a list of components that you cannot disconnect by pulling plug in fuses. These components are protected by electronic fuses. By the way, in stead of pulling the plastic fuses one can measure the drop of voltage between their poles (if you can get to them with a thin probe), indicating the current running through them. There's tables for that.
I was able to narrow the issue down to the read SAM. After some more testing I found a door sensor that was not "closing". Replaced the switch and voila, the CAN bus goes to sleep and the current consumption drops almost to normal.
There is still an issue with the lights. Now the parking lights don't flicker any more but the right side don't turn off when the car is locked.
To turn them off I have to unlock the car, turn the key, turn ON the headlights and then turn them OFF again. But as soon as I lock the car, the right side goes on again.
If I push the parking lights button, the left side switches on or off as intended.
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Great to read. You mention 'pushing a parking light button'. Is the car an R230? No buttons to be pushed there, just a rotary switch.
If the car is an R230, are you aware of the fact that turning the rotary switch to its stop turns on parking lights? Switch vertical = off.
Last edited by Frederick NL; 02-09-2023 at 06:21 AM.
I was able to narrow the issue down to the read SAM. After some more testing I found a door sensor that was not "closing". Replaced the switch and voila, the CAN bus goes to sleep and the current consumption drops almost to normal.
There is still an issue with the lights. Now the parking lights don't flicker any more but the right side don't turn off when the car is locked.
To turn them off I have to unlock the car, turn the key, turn ON the headlights and then turn them OFF again. But as soon as I lock the car, the right side goes on again.
If I push the parking lights button, the left side switches on or off as intended.
02-07-2023, 07:48 PM
