Question on Roll Servo & Roll Trim

Using Garmin GSA-28 servos, I?ve been struggling to get the proper wiring for the roll and roll trim completed. At issue is that the harness supplied by Vans does not comply with Garmin?s recommended wiring.

With this in mind, I?ve decided that I need to build my own harness as many here have suggested. Unfortunately, that?s not as easy as it appears. While building the harness itself takes little time, the knowledge of how/what to wire has been quite time consuming. I?m hoping that the answers to this post will help me complete the task.

Below is Garmin?s recommended wiring diagram. Note that the wires back to the roll motor (#13 & #14) are twisted and shielded. Van?s harness does not provide this. My questions are:

? If you wired these units as per Garmin?s drawing, where did you ground the roll trim end of the shield (red arrow)? The drawing below comes from the G3X installation manual (Revision AJ) page 409.
? Did you use the Molex connectors at the root or use a D-Sub connector?
? If you used a Molex, what pin placements did you use?
? If you used a D-Sub connector, how did you secure it to the wing root?

• Does wire size make a difference where not depicted?

Not implying that you are not 100% correct but most everybody I know used the Vans harness and it works just fine. The red ground goes to aircraft ground or forest of tabs on the firewall. If you are going to abandon the Molex connectors, I would look into using a round CPC connector (series 2) that uses DSub pins.

I am a 7 owner/builder and have TT, but that shows a shield ground and could be grounded to the FOT since it is on the cabin end. Use a solder sleeve with a green or black wire pigtail.

It could also go back to the instrument case via the connector, but mine leads back to the FOT ground directly to the battery (and the airframe along the way).

My vans harness was plug and play for roll servo.