Dome light issue, 2014 LTV FreeSpirit/MB Sprinter 3500

[DaveWA]

I noticed that all lights in my dome light cluster (reading lights, etc) quit working in my 2014 LTV Free Spirit/Sprinter 3500. I checked fuse 19 in the panel under the seat, and fuses 4, 13, 14, 15, and 19 in the foot well and all are OK. I then removed the light cluster and tested for 12v at the connector and it was OK. The engine battery has good voltage (starter cranks the engine right up).

I also noticed that I got an error message on the dash saying that the automatic hi beam system is inoperable (I have now turned off that feature), and the left tail running light was out (but is is NOT). After a few more starts, the error message about the tail light has stopped.

All of these issues came up at the same time. The van has been sitting out in the weather and we have received 5" of rain in January. I have been monitoring interior humidity and it climbed to 80%. I put a DampRid desiccant box in the van and the humidity did drop, but is still too high. I suspect that I may have roof leak, but I do not see any water anywhere.

I did see a thread on the Sprinter forum discussing water leaks that occur at the antennae, directly above the dome light cluster, and am now wondering if all of these problems have occurred because of water leaking at the antennae and onto the PC board in the Dome light component in the head liner. I will work to determine if there is a leak at the antennae.

I went on JustAsk to get a Sprinter mechanic's opinion and he thought that the SAM (Signal Acquisition and actuation) would need to be replaced, but recommended that I take the van to a dealer so they can put their MB diagnostic tool on it to confirm where the problem lies.

Anyone have a similar experience and a suggestion for a course of action?

[DaveWA]

I did replace the dome light module, and this resolved the issue. The dome lights work now, as well as the automatic wiper function and hazard avoidance feature (lane monitoring, etc.) that are apparently controlled by the PC board in this module. I disassembled the failed module and found there was evidence of water and resulting corrosion on the PC board. Since I cannot find any evidence of water incursion above the dome light module, I placed a piece of plastic above the module to deflect any water drips from the roof that may occur in the future.

[avanti]

I had a similar failure and also ended up replacing the upper console assembly. Note, however, that in my case, the leak was NOT the OEM antenna, but rather the crank for the TV antenna, which was behind the driver's head. It is downhill from the ceiling to the console and leaks can travel a long way above the ceiling. You might want to check for leaks further back.

The plastic shield is smart.

[DaveWA]

Thanks! I will check the TV antenna. Mine is over the passenger seat, but the cables may run towards the middle of the van and over the console light module. The OEM antenna cables certainly do have a low point apex of directly above the module. I wonder if even condensation on the the inside of the metal roof might gather and drip onto these cables, which in turn drip onto the module. Time to inspect all seals on the roof at any rate as the van is nearly 7 years old and I doubt that previous owners did much roof maintenance.

[Neil McCubbin]

Where did you get the new PC board?
Any cheaper options than MB dealer?
BTW our nearest dealer is 200 miles à away. We are North Vancouver Island’s

[DaveWA]

Originally Posted by Neil McCubbin

Where did you get the new PC board?
Any cheaper options than MB dealer?
BTW our nearest dealer is 200 miles à away. We are North Vancouver Island’s

I ordered Overhead Console - Mercedes-Benz 9069000300647j69 (Replaces 906-900-03-00-7J69) from Oregon Mercedes Parts, $314.73 USD in March 2021. This one is for vans WITH rain sensor.
https://www.oregonmercedesparts.com/...LTAwLTdKNjk%3D

I tried this URL today and see that it says that "the store is temporarily closed" and that the part is discontinued. When searching the web using that PN I do see other sources with the part available.

Be careful that this PN really does work for your van however. I would suggest that you provide your VIN to a Mercedes dealer to confirm which part that you need as there are different configurations of this board.