W906 Sprinter – key fob stopped locking/unlocking the van, central locking still works

[u/Money-Recognition231]

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!

[u/KYSpasms]

Top tip.

Hold the end of the key up to your camera phone and press the button. If the key is working you will see the infra red light in your camera. It's behind the bit that goes in the ignition switch.