Yesterday I wasn't getting any power to the flap motor through the GAD27. Though that it might be a config issue, so I set the speed scheduling to deploy flaps at max 100kts, but it still didn't work. Then reasoned that maybe it needed a signal from the flap position potentiometer, which I haven't installed yet.

I asked last night on VAF. Everybody agreed that wasn't the issue, and I got some really helpful suggestions on troubleshooting.

This morning, I started checking wiring, starting with the switch. Switch good, so I made a set of jumper wires with the appropriate D sub pins so that I could check continuity all the way to the other end.

Wire job good from the switch to the aux connector that most of the stick and panel switches get pinned into, most of which come out the other end of the aux connector and go into the main wire bundle to continue on to the GAD27.

I was going to check continuity from the Aux connector to the GAD 27, but when I looked at it, it was immediately obvious that there were no pins n the aux connector holes that were called out in the pinout diagram for flap switch signal in.

How it's supposed to work; The switch pulls to ground instead of power. In my pinout diagram from the avionics shop, they have the leads from the switch going to pin 24 & 25 on the aux connector, then those positions on the mating half of the aux connector go to GAD connector 271-1 pins 18 & 19. Move the switch up and it grounds pin 18 which tell the GAD to retract the flaps, move the switch down and it grounds pin 19 telling the GAD to lower the flaps.

Like I said, there were no pins in position 24 & 25 on the 1/2 of the aux connector that had been prewired when they fabricated my main bundle. I initially assumed that they had gotten off by a hole when they pinned it, but when I referenced against my pinout diagram, there were no pins in holes that should have been empty. I then counted the number of pins in the connector and came up two short.

Pulled the Gad 271-1 connector and there were empty holes in that end as well. Specifically position 18 & 19 were empty. What the heck?

Pulled the backshells off both connectors and started identifying wires. Discovered that pair of wires had never been installed. With the jillions of wires running every which way in this full garmin IFR monster, they just missed these two when they built this bundle up on the bench.

When they were building this, they bench checked it and it was all good as far as the CAN bus and the avionics, but they evidently didn't put power on the GAD and confirm all the individual stuff that might plug into it, not that I would have expected them to.

Spent a while cutting off a bunch of zip ties and loosening up some adel clamps. Fished two 22awg wires into the bundle and pinned from position 24 & 25 on the aux connector to GAD27 271-18 &19. All good. Checked with a meter and then plugged in, temporarily wired to the flap motor and verified the switch runs it in the appropriate directions.

Spent the next hour or two verifying that the rest of the switches send power where it's supposed to go.

Spent the remainder of the day wiring discrete inputs into the GAD27 connector 271 while I had it apart. As of now, I have discrete inputs that will trigger a CAS message for the following:

Pitot heat
Stick start button armed
Battery fault
Parking brake on
Carbon Monoxide warning
Event marker

The last one is a suggestion from Levi Self. There is a tiny little flush button below the trigger that is out of the way and I was toying with the idea of making it a remote ident. In talking to him, he said on his own airplane, he has a discrete input that's just labeled "Event" if something happens like an engine bobble or whatever that would make him look at he data later, he just hits the event button and in makes it easy to find that exact spot in the data later. Souded like a great use for that button, so I did the same.

I'll annotate this elsewhere, but the stick functions are as follows;

Left Thumb - remote start relay
Hat - Trim
Right thumb - A/P disconnect /CWS
Trigger - PTT
Index below trigger - Event mark
Low thumb - TOGA