Loss of power to the master switch

[rainman]

Ladies and Gentlemen, I'm technically stranded in Michigan (Y47). On Friday I had my mechanic at my home in Texas change out the four year old Gill battery in my 1979 231, with a new Concord battery. When I went to fly on Sunday nothing happened when I turned on the master switch. No CBs had popped. The dome light and clock still ran. Later that day, my hangar neighbor came over and took the top off the battery box and the battery tested good, he then found a loose ground wire from the battery box and tightened it and the problem was gone. Good deal, problem solved, I thought. Yesterday I did a 0415 departure and had an uneventful flight to my fuel stop at KARG. After fueling, when I got back in the plane...wham the same problem, no power to the master switch. I removed the access panel an checked the same wire, but it was tight. I tugged on several of the wires and then noticed the power had come back to the master switch. I closed up the access panel and started the plane and flew to southeast Michigan to see my ill sister (she should be O.K.). Now that I'm here, I don't want to fly again until I know it's fixed and probably should not have taken off from my fuel stop in Arkansas. Any suggestions? Nothing seemed loose to me (not a mechanic), could one of the cables be bad? Y47 is a small airport but the staff is very nice and have arranged for a mechanic to come from somewhere else to check on it later today. Any obvious things to check or tell him? I'll report back any findings later today. Ray

[Guest]

It sounds like either a bad relay, bad switch or bad wiring.

The master relay control circuit is normally powered by a small wire on the same side as the power wire from the battery.  The other small wire goes to the master switch, when you turn on the master switch you are providing a ground to complete the control circuit.  

Check the condition of the first small wires at the relay at the battery, check the condition of the wires at the switch, you can bypass the switch by taking a jumper wire from the switched side of the relay to ground, the relay should close.  You can also ground the control wire at the switch to test the circuit and wires to that point. 

Clarence

[Drew_Wagner]

I just had the same problem. It was the relay (battery/master solenoid). If you have recently replaced it with the SkyTec, call them and they will send you another one. If you are engaging the switch and hearing the click but getting no power test voltage in front of and behind the solenoid. If you are getting no voltage behind the solenoid but heard the click it's more than likely the solenoid. On mine I could cycle the switch a few times and it would engage but there was about a 1V drop across the solenoid. Apparently it wasn't fully seating so some arcing and resistance was occurring inside the solenoid. Funny thing was that when it did engage the voltage was always different because each time you engage it lands a bit different.

Not a mechanic or as experienced as Clarence!

Sent from my iPhone using Tapatalk

[Yetti]

I vote master solenoid.  The other thing to check is that the battery terminals should all be shiny bright.  As in take a wire brush to them.  Make sure they are all tighten properly.

[Yetti]

Also check all the wiring to the master solenoid sitting on top of the battery box...    Even though a large crimp on terminal looks OK, it can be corroded inside and not making contact.  

[rainman]

Thanks for the input, I'll be there when the mechanic does his diagnosis and will give feedback on what he finds. Ray

[markfoster7700]

Ray,  I used to be based at Y47 and I owned an Ovation 3.  I still have my hangar there and was just out there yesterday and saw your 231 on the ramp.  I'm with the master relay/solenoid group, but Tim (the mechanic who will likely be working on your plane) will figure it out for you.  If I can be of any assistance (ground transport, tools, parts runner, anything), please do not hesitate to contact me directly.  Cell phone is 248-981-3536. Mark Foster  

I am available all day, live 6 miles from the airport, and am happy to assist a fellow pilot who is AOG.  I've had (more than) my fair share of AOG situations with little to no assistance (not with my Mooney, BTW. :-) ).  Call or text if I can help.

[markfoster7700]

Oh, and how could I forget.....we also have an airline pilot/mechanic/Mooney-owner (C model) on the field.  I can look him up for you if you would like. (Jeff at the airport probably already has -- could be the mechanic that he is getting for you.)

Edited September 13, 2016 by markfoster7700

[Andy95W]

Yeah, that's me and I've got the day off and was planning to be around the airport today anyhow (I've got no life outside of airplanes I guess).

248-912-5275

I'll bring my voltmeter and we should be able to isolate the problem to relay, switch, or wiring.

Edit- just texted with Jeff, he's got you set up with Tim who is a local gypsy mechanic and a really good guy.  I'll probably see you out there regardless.

[carusoam]

Some of the coolest and most skilled MSers are airline pilots and mechanics in one human package! 

Best regards,

-a-

[FlyWalt]

1 hour ago, carusoam said:

Some of the coolest and most skilled MSers are airline pilots and mechanics in one human package! 

Best regards,

-a-

Now I wish I had gotten my A&P license. i didn't know that my "Coolness Level" could be even further enhanced :-)

[rainman]

Special thanks to MSers Mark and Andy who came to the hangar to help. The mechanic Tim did a very thorough examination testing the solenoid, relay, and each of the wires.  Rather quickly Andy, Mark, and Tim found a very loose multi-pin connector that was the culprit. It was under a bundle of wires and the one with the most nimble fingers reconnected it. The photo shows 1/2 of the connector. Great response online and in person! Thanks! Ray

[rainman]

Let's try photo again

[carusoam]

Wonderful power of MS!

Thanks for sharing the details.

Best regards,

-a-