Massive battery drain command headunit (Repair)

greekCL

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Hello guys,

The E55k decided to drain the battery over night.
I took it to the autoelectrician to have some tests. And we have found out the Headunit is the one draining the battery.
(hint is that it will not switch on at all...) cannot adjust my clock dials either etc.

Are there people out there that repair the headunits?

Cheers
Vasilis.
 

Alfie

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Its not necessarily the head unit.

The head unit is part of the MOST network. This is a fibre network that runs around the car. There will be other devices on the network that talk to the head unit. These devices use a system of wake up messages, so when one of them comes on (or stays on) it wakes the others up. It is highly likely that one of the other devices is waking up the headunit or others and this is causing the drain. If you take the head unit out or remove the fuse then all that does is to stop the headunit waking up (by another device) or waking itself up. Also its possible that there is a fault in the wakeup wiring somewhere which is causing a device to come alive. Dampness is the usual cause of this.
 
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greekCL

Active Member
Joined
Jun 15, 2008
Messages
498
Location
Kent
Car
Mercedes E55 W211 (2004), BMW 640d GC (2016), BMW 645Ci (2004), Mini Cooper D (2008))
Its not necessarily the head unit.

The head unit is part of the MOST network. This is a fibre network that runs around the car. There will be other devices on the network that talk to the head unit. These devices use a system of wake up messages, so when one of them comes on (or stays on) it wakes the others up. It is highly likely that one of the other devices is waking up the headunit or others and this is causing the drain. If you take the head unit out or remove the fuse then all that does is to stop the headunit waking up (by another device) or waking itself up. Also its possible that there is a fault in the wakeup wiring somewhere which is causing a device to come alive. Dampness is the usual cause of this.
Oh I agree it is a network of many components.

However the headunit does not power up at all... The screen has no signs of life at all.
Hence I am talking about the headunit.
It glows hot in the thermal scanning though.
However when it is unplugged the drain goes away.

Sent from my CLT-L29 using Tapatalk
 
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greekCL

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Mercedes E55 W211 (2004), BMW 640d GC (2016), BMW 645Ci (2004), Mini Cooper D (2008))
are you not better off with something like this, as opposed to repairing or replacing the Comand unit?

Mercedes-Benz E-W211 Stereo 7" Android 8.1 GPS SAT NAV Car DVD Player Head Unit | eBay

I have to say the aftermarket units do not appeal to me :( ... if it was my only car then I would do it.
But since this is a "weekend car" I would like to keep it a stock as possible in that aspect. (apart from changing exhaust)
 

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