I just picked up a bargain buy of a 2004 E320 4Matic Wagon. It runs and drives great but there's lots of issues I'm working thru 1 by 1. I'm stumped by one that's keeping me from putting it on the road: No brake or tail lamps.

Here's what's up:

No brake lights, EXCEPT the center high mount light, which does work.
No tail lights
No rear turn signals
No tail gate interior light

There's a number of things at the rear that do work: center high brake light as stated, rear fog light, license plate light, reverse lights, rear wiper, rear latch electric release and closure motor, rear defrost.

OBD shows tail gate control module (SAM) not reporting on CAN. It specifies the N111 SAM located in the tail gate, not the main rear SAM with the fuse box in the left side rear cargo area.

There's +12V at the tail gate SAM on both the standby and accessory 2v power wire.

All grounds at the tail gate SAM are good

All grounds at every bulb connector is good

All bulbs light when connected directly to 12V

The electrical mechanisms for the rear tail gate latch work, both to release the latch and pull it to final closed position. I mention this because power for these passes thru the tail gate SAM.

Given all of this, I concluded that the tail gate SAM had gone bad. It's getting power and is properly grounded but isn't reporting to CAN or turning on any lights it's supposed to .

So i find a salvage part online and plug it i hoping it solves the problem. It does not. Symptoms are identical, so it's not the tail gate SAM.
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I took the covers off the SAM thinking I might see corrosion or burn marks on the circuit board. I found nothing that looked off

So next I stripped out the rear SAM from the cargo area thinking I might find corrosion or burns. Nothing

I'm lost as to what to do next except the dealer, which I'm loathe to do because my experience with my local dealer is that they very much pursue a mentality of 'let's start changing stuff and see if it helps' and it has cost me a whole lot of unnecessary expense on my CDI.

There is one other conspicuous error showing on the OBD. It's error code 930E and states 'signification synchronization of the DTC memory cannot be ensured

 

duplicate post... see my answer here ....