I solved the Problem 😄

You have to PullUp the Pin than it will work.

i upgraded the firmware to RFF3.1.1, now i have the problem with the always triggered on everey Pin, even on e1stop, witch didnt had that problem on 3.0, i switched back and the e1stop is working but the expansion pins dont.....

@Deltasquare said in Did I kill my DuetWiFi?:

So I have a new board now. Just to make sure this time:

If I run a 24V System, I can only set the voltage to 12V on the DueX.

By "I can only set the voltage to 12V on the DueX", do you mean you can set the Fan voltage to 12V on the DueX but not on the Duet? If so, that is correct.

For this purpose we have the jumper on the Duex. If I set it I can power Fans as well as LEDs from Duex

Correct, if you connect the LEDs to spare fan outputs.

however, the Duex does not act as a constant power source for the LEDs.

Do you mean that you want some "Always-on" LEDs? The most recent DueX5 revision has a 12V always-on output (when the 12V Enable jumper is in place). For other DueX5 revisions, with the fan voltage selection jumper set to 12V you can connect a 12V always-on fan or LED between the VFAN pin of any fan output and the ground VIN connection.