Status LED on Pixhawk safety switch not working

I am using a 3DR Pixhawk, PX4 on a DJI F450 frame. The status LED on the safety switch is not illuminating, but it seems that the switch is functioning (for example, when running the ESC calibration procedure, the switch enables power to the motors). The switch is brand new. I purchased it from JDrones, the only supplier I could find in the world making this switch. I have contacted JDrones to inquire how to test the switch, and we’ll see what that brings. However, by searching this forum, I also found that several others have recently experienced safety switches that have been mis-wired. The wiring diagrams however appear to be related to a different controller, with a J17 connector. My pixhawk has a DF13-3P connector.

Attached is a picture of how the switch that I received is wired. Could someone take a look and tell me whether this wiring is correct or not? Thanks much.

Does this link help:

Hey Micke,

The link is certainly related, but I think not quite what I need. I had looked at it before making my original post. The safety switch diagram and pins are identical to what I have, however the link describes connecting the switch to the PX4IO J17 pin, and I don’t have that. I have a Pixhawk with a DF13-3P connector. I don’t understand enough to know the differences between the two setups. I’d appreciate any further guidance that you or anyone else might offer, as I’m stuck at this point.


I guess I’m confused. The PX4IO module is a module inside the Pixhawk? I found this schematic

It shows the following scheme for the safety switch:

Lo, and behold, the DF13-3P connector is shown to the right - maybe this is the very same connector that I see on top of the Pixhawk? If so, the LED wire appears to be connected to the middle (#2) pin on the pixhawk. And, that is the way the safety switch was wired.

This leads me to believe that either A) the LED or some component of the wiring within the safety switch is defective, or B) the Pixhawk circuitry is defective. How to test?

Do you have a multimeter? Usually multimeters have a diode test mode (one of the ohm scales with a diode picture), which when connected to an LED will provide some current to light it up. If the switch is OK, if you connect the positive lead to pin 1 of the DF13 connector and negative lead to pin 2, the LED should light up slightly. If it doesn’t, try other combinations, maybe it is miswired.

Thank you Arthur. I do have a digital multi-meter, but unfortunately it does not have a diode test feature. I suppose I could simulate the feature by using a battery and some wires. Not sure what voltage to apply. 3 volts?

3 - 5V should do, but you need to connect a 200Ohm - 1kOhm resistor in series to limit the current and not burn the LED.

If the switch is functioning but no light.
Then just swap LED wires.
Switch has no polarity but a diode does.

No need to use multimeter, see diagram
*white dot = pin no.1 (LED gnd. 3,4---->|----1)

Multimeter should be able to test a diode with short circuit test mode, it won’t beep when reversing polarity

Thanks, Pitt. I agree with you that I could experiment with swapping wires, etc. But, at this point, it looks to me as if the switch is wired correctly. And, since I just bought it, I’m afraid that if I start picking it apart, and damage it, that I will not be able to get a replacement from the seller. For now, I’ve ordered a cheap multimeter and will test it without taking it apart. Thanks.

Some multimeters test diodes in continuity(beeper) mode, some in 2kOhm mode. In any case, none of the multimeters I have beep when a diode is connected as diodes are not ideal conductors. The diode test mode is useful in this case because it provides enough voltage and current to dimly light up a LED.

I ordered this multimeter on Amazon. Looks like it should be able to test the LED without my having to take apart the new switch. Thanks for the help.


I got the multimeter, and was able to test the safety switch. Applying the black lead to pin number 2 on the safety switch, and the red lead to pin number 1 on the safety switch, the LED lit up. This confirms, I think, that the wiring is correct, and the switch is in good order. It leads me to conclude that there is something wrong with my Pixhawk.

I took the pixhawk apart, and see that I have the PX4FMU v2.4, With the safety switch connected to the plug, I was able to test using the diode test mode below the plug and socket connection on the board, and the result was good - the LED lit up. So, the connection appears to be good.

I am in the process of downloading Eagle CAD software in order to view the schematics for the PX4FMU v2.4. Maybe I’ll learn something about the wiring. But also, I took the board out of the case, and applied DeoxIT to the soldered connections in the vicinity of the safety switch connection. Maybe I’ll get lucky. It did look a little corroded in that vicinity, though I think this might be wishful thinking.

I also noticed that there is a Pixhawk debugging tool. Do you know of anyone that would test a Pixhawk to see if it is working 100% OK or not?


I re-assembled the Pixhawk and made the necessary connections. All is working now!!! Not sure about this, but I’m thinking that the Deoxit may have done the trick!

My son and I were able to arm the copter and we tried to take off, but the copter started flipping over on takeoff…Next problem to solve!

Thanks for all the help!


I use these
they have the switch, buzzer, usb and 12c port. I made a little case on my 3d printer to house it outside the cover of my X6. and i have it on 3 other pixhawk drones. I works great.

So there seems to be no major fault with the hardware, that sounds good.
I’m not familiar with Deoxit (seems like some contact cleaner product), but if the problem is with the solder joints and not the mechanical contacts, it would be better to touch them up with a soldering iron.