M20K Gear Down Limit Switch

[Wingfree]

Recently, the "Gear Warn" breaker started tripping intermittently on my 1979 231.  I was unable to find a pattern of when the breaker would trip.  In the air, on the ground, engine on, engine off... I had not been able to find a root cause. 

Now, the breaker pops immediately when Master switch is turned on.  After spending the weekend troubleshooting with my A&P we were able to prevent the breaker from popping by turning on master, raising the gear (down limit switch not pressed, turning off master and reseting breaker, turning master back on and breaker stays put; as soon as the gear goes down and paddle pushes in the down limit switch, Gear Warn breaker trips.

I've started researching in case I do need a replacement switch.  The IPC lists P/N 1CH116-6.  Is that the same as 1ENS1 and also MS324331 and also P6-24014 and also 21649 or are all of these different?  Prices are all over the place.  Used ones are $60-$300 and new is $600-$1,200.  Anyone know of an alternate part number I can search for?

What are the chances that the gear down limit switch can cause a short and pop the gear warn breaker?  Could a failing breaker behave like this?  Anything else we should check before swapping out the down limit switch?

Appreciate your help!

[N201MKTurbo]

The gear warn CB has nothing to do with the actuator. It is all in the lights and horn, and I think the primary side of the contactors. I suspect you have a short somewhere in a NO circuit in the limit switch. Should be able to find it with an ohm meter.

[Wingfree]

Thanks!  We brainstormed about that possibility but it's the Gear Warn breaker that pops, not the one for the actuator.  

[Wingfree]

Thanks N201MKTurbo! 

[MikeOH]

1 hour ago, Wingfree said:

Thanks!  We brainstormed about that possibility but it's the Gear Warn breaker that pops, not the one for the actuator.  

Ooops!  My reading skills appear to be impaired...I've deleted my useless post.

[skykrawler]

On 9/12/2024 at 9:32 PM, Wingfree said:

Thanks N201MKTurbo! 

So you found the problem?   Please share.

 

[Wingfree]

8 minutes ago, skykrawler said:

So you found the problem?   Please share.

 

It was a short in the gear down lamp holder (floor indicator light).  Mechanic resoldered the lamp holder and that fixed it… until it shorted again. Then traced it to the led bulb also shorting out with the lamp holder case. We swapped back to the conventional bulb and no more short or tripped breaker.  I have a new lamp holder coming in to see if that’ll work with led bulb otherwise sticking with original bulb type. 

[skykrawler]

So it was simple.  Which is good.