EMS Wiring

Time: 8 Hours

I had a great day in the shop yesterday working on the EMS(Engine Monitoring System). This Dynon module allows you to electrically input information from many different items like oil pressure, fuel pressure, exhaust gas temps and other things that you want to see on your screen. The really cool thing about Dynon is that they allow you to make widgets on the screen in various configurations for the inputs that you connect. For example on my RV I will have my pitot tube heated which is controlled by a switch. However I would really like to know that the unit is getting the power and heating once I turn on the switch. The heat controller has a signal wire, that when the pitot is getting electricity and heating becomes active, that I will connect to one of the EMS inputs. Then I can create a widget on the screen so that when the pitot heat is off it will be black and when on it will be green so that I have a clear indication that it is working. So first thing to do was remove the shelf I made for the module and drill for the attach hardware, nutplates in the forward side and holes for screw/nut on the aft side since they will go through the cross member brace. 

For the rest of this installation my process was to determine which wires need to stay behind instrument panel in which wires needed to go to the firewall forward.  Once I had that information I determined the length of the harness so that I would have easy access to it should I ever need to work on it and clamped it to the baggage area panel.

With the harness connector secured I started the process of separating the wires that would go to the firewall forward and the ones that needed to stay behind the panel. 

As I found the ones that needed to stay behind instrument panel I went ahead and made those connections to the respective wires, like the pitot heat controller and other items, with a butt splice connector. 

The wires that were heading to the firewall forward I just hung over the firewall to organize them.

One thing that helped was taping the layout for a fuel injected four-cylinder Lycoming set up to the rollbar and highlighting the completed wires so that I knew which ones had been completed.

Dynon builds these harnesses to meet many different configurations so I will end up with a bunch of wires that won’t be needed. So those wires I flipped to the opposite side to organize them. I could cut or remove them however I thing I will just bundle/secure them out of the way for future adds if needed. 

Once I had all the wires connected behind the panel I connected the harness to the module in ran the wires that needed to go to the firewall down through the gear tower and forward through the firewall penetration hole. I cleaned up the wires with zip ties and coiled up the unused wires and secured them as well (they look like a colorful doughnut). 

The second harness on this module has wires that run to the firewall forward for the EGT (exhaust gas temperature) and CHT (cylinder head temperature) readings. I split these out to run left and right, the #2 & #4 cylinders are on the left side of the aircraft and the #1 & #3 cylinders are on the right side of the aircraft.  

On the left side I wrapped the 4 wires in heat shrink to protect them before they exited the firewall.

Three of the wires from the EMS go to the left and right fuel level capacitors. I drilled holes in the left and right side of the fuselage and used a rubber grommet to protect the wires it will put a three place Molex connector on these similar to the other connections I have done. 

I made a measurement to see how much extra wire I would need for the fuel level wires and made the cut. For these wires I will have the majority of extra length on the fuel tank side vs the fuselage side since I don’t want to have the extra wire showing in the cockpit since this area will be somewhat exposed.  

So now the only wiring I have left in the left wing will be the OAT temp probe, if that’s where I end up installing it. 

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