parasitic battery drain cls 500 w219....schematic anyone?

[matteb63]

I've narrowed the drain down to two rear 7.5 amp fuses
F3 and F8 in the boot ..

3	TPM [RDK] (tire pressure monitor) control unit PTS (Parktronic) control unit Navigation processor TV combination tuner (analog/digital)

8	Left antenna amplifier module Alarm horn Alarm signal horn with additional battery ATA [EDW] inclination sensor

when I remove these the drain drops right down but I need to chase the connections and think I need schematic if someone can help ..thsank you..also cant lock doors with the key when they are removed

 

[MJJ]

The alarm horn is quite a common source of parasitic drains. My S211 (same platform underneath as yours) had this issue, the rechargeable battery in the alarm horn ages, always appearing to require charging to the car, and this then keeps the vehicle CAN network awake - draining the battery.

Disconnecting the alarm horn (behind NSF wheel arch liner on pre-FL, OSF on facelift) solved it instantly on mine.

If you really do want to track down schematics, search for WIS (Mercedes service tool) online or on ebay. One word of caution though, the battery drains tend to be faults in modules keeping the CAN network awake which is not necessarily possible to 'see' from a schematic. Diagnostics will pinpoint faults trapped by the modules themselves on the car.

Martin.