You are absolubtely right about reverse polarity consequences, even though I can almost guarantee both are the same, I have no experience with that particular unit, an option would be to do a cointinuity check across both red wires, or try to see if you confirm both cables are soldered to the same end on the circuit board. WAIT! WAIT! WAIT! I'check on the FADEC forum...

Just BE SURE your's is a NADES unit, here is your asnwer.....http://www.xicoy.com/foros/index.php?topic=223.0

Glad to Help!!!