1975 Mooney M20F weird electrical issue

[Htmlkid]

So I'm having a issue where when I shut down the plane the electric doesn't shut off till the stall horn breaker pops.

Any thought????

[ShuRugal]

Can you elaborate more on that? What's the sequence of events from "master switch off" to "everything de-energized"?

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[cliffy]

Did this show up all of a sudden?

[carusoam]

1) The stall horn only comes on with the master…

2) If you turned off the master, and the power stays on… that is a faulty master relay that needs help…

3) The wiring diagram is very simple and in the plane’s POH…

4) The relay not working correctly, probably is sending power where it shouldn’t like through the stall switch to ground…

5) Figure it out, or go direct to your mechanic with the wiring diagram…

6) testing the relay with a voltmeter is pretty easy…

7) Check how old the master relay is… if it is 50, go ahead and replace it… they are expensive and can have long lead times… or be hard to find…

PP thoughts only, not a mechanic…

Best regards,

-a-

[Htmlkid]

22 hours ago, ShuRugal said:

Can you elaborate more on that? What's the sequence of events from "master switch off" to "everything de-energized"?

Sent from my Pixel 3a using Tapatalk
 

So when I shut down and the last thing I do is turn off the master.... the electrical power stay on until the stall horn breaker pops which it about 10 seconds later????

[ShuRugal]

So when I shut down and the last thing I do is turn off the master.... the electrical power stay on until the stall horn breaker pops which it about 10 seconds later????

That sounds like your stall horn circuit is bypassing the master relay and powering your plane? Get an electrician to look at that, crossed circuits and faulty grounds are no joke...

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[cliffy]

19 hours ago, cliffy said:

Did this show up all of a sudden?

I ask again above       the answer makes a difference

[Htmlkid]

16 hours ago, ShuRugal said:

That sounds like your stall horn circuit is bypassing the master relay and powering your plane? Get an electrician to look at that, crossed circuits and faulty grounds are no joke...

Sent from my Pixel 3a using Tapatalk
 

Its in annual now and I have notified the mechanic.

 

Thanks

[Yetti]

On 10/11/2021 at 2:28 PM, Htmlkid said:

So I'm having a issue where when I shut down the plane the electric doesn't shut off till the stall horn breaker pops.

Any thought????

You have a bad ground on the battery or one of the other main ground straps.   So basically the whole plane is trying to ground through the stall horn which of course is too much amps and pops the breaker.  

[Yetti]

Check that the solenoids in the battery compartment are grounded well.  Clean and make shiny the battery ground to start with.