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Garmin OAT GTP-59 left wing

JDA_BTR

Well Known Member
So it seems the wiring harness forgets this probe, even looking at the fuselage harness layout for Garmin options. Even if you build a different harness to the connector you don't have enough pins at the wing root to get a GMU22 and the OAT done.

GMU is 7 pins (two are grounds)
OAT is 4 pins (one is ground)
And then there is the pin for the stall warn switch.
Total: 12 pins needed and there are 9

So can the three shield/signal grounds be combined? Still gets you to 10 pins and one too many.

I wonder if anyone has solved this in a nice way?; I'm sure I'll be told to abandon the van's wiring but it's already in the wing.
 
I can't remember the details but I used the supplied wing harnesses and my GMU & OAT just plugged straight in. I never understood all the calls to abandon the supplied harness :confused:. The only thing I changed was to ground the strobe back to the wing root to stop interference with the GMU22.
 
Also on my drawings, the ground from the strobe goes to the landing light where it connects to the ground on the light; that yellow wire goes to the wing root and to ground. So the strobe and landing light share a wing root ground line. Is that how you had it originally? There is also a white wire at the landing light that is unused in my configuration (don't use the landing light control line) and this runs back to the wing root too. I suppose you could use that for a separate ground line or something else.

I might use that pin on the connector to take the stall switch, free up a pin in the other connector for the GMU and GTP, and make it all work. I think that if I float the shield ground from the GTP the same way the shield ground is floated from the GMU the wiring can work fine.
 
As Graham, I grounded the wing tip strobe-nav to the wing root. I added shield wires for OAT and changed the green-red-yellow wires of the Van's kit by shield wire to control LED wing tip strobe-nav. When it was possible I modified pin's on Molex connectors.
 
I faced the same problem then measured the length of cable providered by Garmin. Turns out the probe will make it to the hole provided by Van's in the first inspection bay so I will just ran the cable without cutting it. Will write a note in the stub wing to remove the probe before pulling the wing.
 
I spoke with Stein and he said it was ok to cut the cable and put in a connector if you wanted. I am making sure that all wires have connectors so that the wings are removable if necessary without cutting anything, that's the only was to assure that the wings will never need to come off. :)
 
Also on my drawings, the ground from the strobe goes to the landing light where it connects to the ground on the light; that yellow wire goes to the wing root and to ground. So the strobe and landing light share a wing root ground line. Is that how you had it originally? There is also a white wire at the landing light that is unused in my configuration (don't use the landing light control line) and this runs back to the wing root too. I suppose you could use that for a separate ground line or something else.

I might use that pin on the connector to take the stall switch, free up a pin in the other connector for the GMU and GTP, and make it all work. I think that if I float the shield ground from the GTP the same way the shield ground is floated from the GMU the wiring can work fine.

I recall now that the OAT cable was long enough to run all the way from the panel to the wing. If I ever have to take the wing off it should be easy enough to remove the probe from the wing.
I just piggybacked the strobe ground onto the landing light ground and that worked fine. The earlier drawings had the strobe grounded at the wing tip.
No pitot heat yet but plan to add soon (made a mistake not adding it originally)
 
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