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Mercedes W220 S320 cdi 2004
654 Posts
Discussion Starter · #1 · (Edited)
In case it’s of interest to anyone here with a similarly regular & frustrating W220 issue..😣

You might remember my recent Battery Drain Tales of Woe - which my auto electrician eventually traced to a faulty / 'stuck' boot (trunk) manual release button - and its electrical connection to the boot interior lights amongst other components in the PSE system.

In the fault-finding process he removed the boot lining & disconnected / physically unbolted & reconnected the COMAND Navigation CD & CD multi-changer units to check them for bad connections / earths etc which might also cause the battery drain?

His Verdict: after testing for excessive Battery Drain from those & various other components (ECUs etc - all ok) the issue seemed to be that Bl**dy ‘stuck’ boot button & its electrical connection to one or all of the 3 boot interior lights (2 x 10w under the bulkhead + 1 x 5w in the boot lid) which was causing any or all of them to stay ON permanently - hence the drain. Only a 2 minute Fix after 3 hours of investigations :eek:. But Hey Ho, it's an 18 year-old W220 after all?😕o_O :ROFLMAO:.

Solution: Elec connection from Boot release button isolated and all has been fine since. The Boot still opens reliably via the remote key & internal switch in the Driver’s door, the 2 boot interior bulkhead lights switch on / off automatically when opening / closing. So I can live without the manual release button OR the other (3rd) light in the boot lid. Phew!

Getting back to the Interesting bit (COMAND start-up wise):

A month later, my COMAND unit Screen, Radio, Navigation etc start-up quickly & faultlessly EVERY time.🕺 NO more slow-starting and / or ‘freezing’ - as used to drive me Crazy several times per week. I only noticed this today after living with the problem for 6 years...

Conclusion? You tell me…;)

Hope this helps & try to keep smiling on the (sometimes technically baffling) W220 Journey :ROFLMAO:

MB :cool:

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2000 S430, 2000 S500, 2003 S600 TT, 2005 E320 CDI, 2006 S500 4Matic, and 2006 S350
7,830 Posts
Goes to show...the little things really do count with these complex motorcars.
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