I am trying to replace my Goodman control panel (see this question), and have a wiring question.

The new control panel (50M56U-843) that I acquired came with a large variety of wire adaptors. I think I need to use only one of these adaptors (for the ignition?) but the adaptor switches the positive and negative (see images showing connections) which seems weird to me.

I am very much not an electrician, and I'm not sure if this is on purpose because the new board knows they need to be switched, or just they gave me some generic adaptor since the new board updates many old boards, and they expect me to manually swap the wires on the adaptor to match.

  • A few things seem off the 4 prong molex doesn't have any neutrals – Joe Fala Mar 9 '19 at 2:26
  • Well the original only had two wires... maybe new board has option for more, but I only have two from the old board anyway (See all pics). Any hints appreciated. – jlivni Mar 9 '19 at 2:29

Okay here's what to check.

The two wires have reversed colour, ignore the wire colour and compare it to the old connector and trace the wires back. If you can add photos of what component(s) the wires go to. The 4 pin molex I mentioned in the comments seemed odd because IGN = ignitor, IND = inducer, IGN N = ignitor neutral and IND N =inducer neutral. No worries, if the old one was like that it just means they picked up neutral of the neutral bank elsewhere.


In DC electrical like cars, batteries and circuitry red is positive and black is negative. With line voltage red and black both indicate power. And HVAC electrical is a world all on it's own.


I had a closer look at the diagram, there is one more component in there that could be causing the failure. There is a pressure switch called "front cover pressure switch" it has a grey wire and a brown wire one of which goes into the gas valve. I'm not sure what it looks like but it's in the schematic. It interrupts the gas valve power so if faulty, testing at the gas valve wires will give you a false positive on a board failure diagnosis.

Looking for this one

enter image description here

These are the flash codes enter image description here

  • Woah thanks for this great answer. Appreciated. Sounds like we can just plug in the adaptor then w/o switching wires correct? Will do this tomorrow AM and test it out. If it doesn't work I will also research into what this front cover switch is. – jlivni Mar 9 '19 at 4:05
  • As long as the wires are doing the same job the colour doesn't matter. – Joe Fala Mar 9 '19 at 4:08
  • Ok so I switched out the control panel, but unfortunately get the same results (ignitor lights, but no gas comes; no voltage to gas valve). I noticed the brown wire from gas valve goes directly it seems into the control panel power area. The grey wire goes into a switch called 'Blocked Drain', which makes me wonder if somehow the freezing weather could have caused this to get flipped? I don't know how to bypass it or test that tho. – jlivni Mar 10 '19 at 0:28
  • Also happy to $$ you if you can walk me through fixing this stuff over phone or video or something. Image of switch Image: photos.app.goo.gl/RcniA7AKpLCe3h2v5 – jlivni Mar 10 '19 at 0:30
  • 1
    When it shuts itself down count the red flashes – Joe Fala Mar 10 '19 at 2:14

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