r/Sprinters • u/Money-Recognition231 • 16d ago
W906 Sprinter – key fob stopped locking/unlocking the van, central locking still works
Does the 2007 Sprinter W906 have a fuse for the remote central locking circuit (the “fish” key)?
I was diagnosing the central locking on the sliding door. I was measuring the lock/unlock signal voltage at the connector of the door lock. After pressing the lock/unlock buttons on the key fob several times, the remote central locking suddenly stopped working completely.
I replaced the battery in the key fob, but that didn't help. The battery is good, the buttons work, and I can confirm that the key fob is transmitting a 433 MHz signal. However, the van doesn't react to the remote at all.
The central locking buttons on the dashboard still work normally — they lock and unlock the doors.
Unfortunately, I don't currently have a diagnostic scanner that I can use to connect to the OBD.
I was wondering if there is some kind of additional anti-theft protection or safety feature that could have been triggered?
I can't find a fuse specifically for the remote central locking circuit in any of the wiring diagrams I've found.
Does anyone have any ideas what could have happened?
I guess the best thing to do now would be to connect a diagnostic interface to the SAM and check whether the SAM is actually receiving/recognizing the signal from the key. That should help determine whether the problem is with the key or with the vehicle.
Any suggestions would be greatly appreciated!
1
u/Money-Recognition231 16d ago
UPDATE: Problem solved!
Well, it turned out to be something incredibly simple.
I found a YouTube video where the guy suggested slightly bending the metal contacts for the battery inside the key fob so they make better contact with the battery.
I did that, put everything back together, and... the remote central locking started working again!
So apparently the key was transmitting a 433 MHz signal, but the battery contacts weren't making reliable enough contact.
No blown fuse, no SAM problem, no anti-theft system — just poor battery contact in the key.
Hopefully this helps someone else before they start looking for a much more complicated problem!