Sneaky M20C electric gear malfunction

[Mikey30V]

Short version:  Pin 3 in the 4-pin round AMP "squat switch" connector (not the switch itself) had backed out of position in the connector body, producing a high resistance connection going to Squat Switch terminal 1.  This allowed the gear to unlock from the Down position when UP was selected, but would stop the gear motor almost immediately.  No audible alarm was sounded.  Gear went back down and locked when DOWN was selected.

Long version:

My 75 C model exhibited an interesting malfunction on 13 November.  After flying five circuits in the pattern working on speed control on final, the gear refused to retract on the sixth takeoff.  I got a GEAR UNSAFE light but no audible alarm, and the gear breaker popped.  After resetting the breaker the gear lowered when selected, but another try to raise gave the GEAR UNSAFE light again but with no breaker trip.

Figuring that my air-work was over for the day, I selected Down again and got the green lights, subsequently landing and rolling out uneventfully.

On jacks the next morning, the actuator sounded terrible--like it was bound up.  A check of the voltages at the A1 terminal of the Gear Relay showed unusual voltage when it should have been showing zero volts to airframe ground when the gear was going UP.

Further investigation around the left gear leg uncovered the problem in the Squat Switch AMP connector (original to the airplane).  After reseating pin #3 and inspecting and cleaning the connector, gear operation was again normal. 

Suggestion:  If you suspect that you are having a problem with the Squat Switch, locate and inspect the round AMP connector supplying it. Contacts inside an old plastic connector body can move out of position and give intermittent or no electrical continuity.