2016 Mercedes CLS 3.0 Diesel – Flood Damage Electrical Issues (CAN Bus Shorts)
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Mercedes CLS 2016
2016 Mercedes CLS 3.0 Diesel – Flood Damage Electrical Issues (CAN Bus Shorts)
Hi all,
I’m looking for some advice on diagnosing electrical issues on a flood‑damaged 2016 Mercedes CLS 3.0 Diesel.
Background
The car was involved in flooding, with water mainly entering the passenger‑side footwell and a small amount on the driver’s side. The water level wasn’t very high.
After the flood:
The car stalled
The engine seized
The vehicle was left standing for several months before I purchased it
At the moment, I’m only working on the electrical side before touching the engine.
Work completed so far
Full interior removed
Carpets removed
All trapped water drained
Vehicle thoroughly dried
Most water damage was clearly on the left (passenger) side.
Electrical symptoms (intermittent)
Instrument cluster flickers, mainly with key in position 2 (sometimes dims or goes completely blank)
Windows work intermittently and sometimes stall
Main infotainment screen does not work
Power seats do not work
Very occasionally, everything works normally, but this is rare.
CAN bus checks
Replaced the CAN bus star connectors on the passenger side
Driver‑side star connectors didn’t appear badly affected, so I cleaned them with electrical contact cleaner
Disconnected each CAN branch from the star connector and checked for shorts to ground
Shorts to ground found on:
N69/1 - Front Left Door Control Unit
N69/2 - Front Right Door Control Unit
N69/3 - Rear Left Door Control Unit
N69/4 - Rear Right Door Control Unit
N73 - Electronic Ignition Switch (EIS)
N30/4 - ESP ABS Module
When the corresponding module is unplugged, the short to ground disappears on that branch.
Door modules
All four door control modules show a short to ground, which seemed unlikely. To rule out a bad module, I installed a brand‑new door module, but the short to ground remains.
Common link noticed
The common factor appears to be:
All affected circuits run through Connector 7i on the Front SAM
N73 is also routed to 7i via Connector 11c
No corrosion at front or rear sam, the wires and sams look as good as new.
Any advice on next diagnostic steps would be appreciated.
I've attached:
Wiring diagrams for all affected modules
Front SAM wiring
CAN bus topology spreadsheet
Thanks in advance.
I’m looking for some advice on diagnosing electrical issues on a flood‑damaged 2016 Mercedes CLS 3.0 Diesel.
Background
The car was involved in flooding, with water mainly entering the passenger‑side footwell and a small amount on the driver’s side. The water level wasn’t very high.
After the flood:
The car stalled
The engine seized
The vehicle was left standing for several months before I purchased it
At the moment, I’m only working on the electrical side before touching the engine.
Work completed so far
Full interior removed
Carpets removed
All trapped water drained
Vehicle thoroughly dried
Most water damage was clearly on the left (passenger) side.
Electrical symptoms (intermittent)
Instrument cluster flickers, mainly with key in position 2 (sometimes dims or goes completely blank)
Windows work intermittently and sometimes stall
Main infotainment screen does not work
Power seats do not work
Very occasionally, everything works normally, but this is rare.
CAN bus checks
Replaced the CAN bus star connectors on the passenger side
Driver‑side star connectors didn’t appear badly affected, so I cleaned them with electrical contact cleaner
Disconnected each CAN branch from the star connector and checked for shorts to ground
Shorts to ground found on:
N69/1 - Front Left Door Control Unit
N69/2 - Front Right Door Control Unit
N69/3 - Rear Left Door Control Unit
N69/4 - Rear Right Door Control Unit
N73 - Electronic Ignition Switch (EIS)
N30/4 - ESP ABS Module
When the corresponding module is unplugged, the short to ground disappears on that branch.
Door modules
All four door control modules show a short to ground, which seemed unlikely. To rule out a bad module, I installed a brand‑new door module, but the short to ground remains.
Common link noticed
The common factor appears to be:
All affected circuits run through Connector 7i on the Front SAM
N73 is also routed to 7i via Connector 11c
No corrosion at front or rear sam, the wires and sams look as good as new.
Any advice on next diagnostic steps would be appreciated.
I've attached:
Wiring diagrams for all affected modules
Front SAM wiring
CAN bus topology spreadsheet
Thanks in advance.
