Panel wiring harness complete

Continuing the main wiring harness surgery, I remapped the fuse block wires from what SteinAir originally did - eliminating a few more wires from the conduit to the overhead console (e.g. no reason to have separate wires and fuses for the front and rear overhead lights), and adding the Spartan3 AFR sensor (which I kept on the main bus instead of the Bus Manager on purpose - I only want it to start heating the sensor after the engine is running, and it has a mode where it'll start 3 minutes after being powered on, so on my start checklist, turning on the main bus is the last step before hitting the starter (and before that the avionics are powered by the IBBS, while the EFII system is completely independent of the main bus):

Changes to be made to the fuse block wiring

Updated fuse block and wiring

For connecting the door relays, I got connectors that attach together, and wired them directly from the fuse block:

Door indicator relays attached to sockets

Door indicator relay sockets with power wiring

I then chose the position to attach those relays (nutplates will be added later), and laced those wires:

Fuse block, door indicator relays and GAD29 in place, with wire bundle tidied up

I protected the main bus bar (that connects the tailcone solenoids) against accidental contact with heatshrink:

Tailcone bus bar with heat shrink protecting non-contact areas

I also rewired the EDS-4IP's distributors per MH's recommendation, which means a single power wire pair for all of them (the controller's pins are connected together anyway, and all my distributors are near one another, so that saves me a bunch of wiring up to the overhead console:

Updated Mountain High EDS-4IP connection diagram

For the Spartan 3 air-fuel ratio sensor, I soldered a Molex Ultra-Fit (172287-2308) connector to the board - the connector is only 8 pins (vs the original 10), but the last 2 pins are not used anyway. This will be much more secure than the original screw-in connector, and as mentioned on the last post I'll 3D print a custom case for it:

Spartan 3 AFR sensor with Molex connector soldered on

I then moved the main harness back onto the panel to figure out its attachment - with Adel clamps on the VP-X screw holes on the left, and figured out the right places to add holes/nutplates for Adel clamps on the right:

Tidied-up GTN/GNX wire bundle, ready for re-lacing

Right-side main wire harness held in place with Adel clamps

I attached and wired the essential bus bar and fuel pump relay to the back of the panel substrate:

Essential bus bar connected to circuit breakers and fuel pump relay

I then decided I didn't like this :) The wires going all the way down to the relay felt weird, so I swapped the relay and the bus bar locations, whch looked much cleaner:

Essential bus bar connected to circuit breakers and fuel pump relay, but swapped positions

Finally, I re-laced the main wire harness, which gave it a nice and secure finish (I'll also add some edge grommet to the subpanel hole to protect it):

Re-laced GTN/GNX wire bundle going through subpanel (still without edge grommet)

Re-laced GTN/GNX wire bundle

Re-laced main wire harness

The only part of the panel wiring that I'm leaving for later are the EFII wiring (since I don't have the LRUs yet) and the breakout connectors. There's also of course the rest of the wiring that's not behind the panel (back to the tailcone, in the tunnel, and firewall forward).

Time lapse:

Total avionics rivets: 59
Total avionics time: 76.3h


  1. Any chance you could post that redesign of the Spartan case? I'm having the same frustration with the screw terminals.

    1. Definitely - it's already linked from this post: .
      As noted in this post, I replaced the connector on the Spartan, so that case design is for the new connector. I had also started a design with a right-angle connector of the same kind, let me know if you'd rather have that (it may just need updating the dimensions to match the design I actually printed).