Sounds like you on the right track Wil.
Some good input.
Keep us posted.
I also found this troubleshooting list concerning the ground.
PROBLEM: Furnace comes on for 7-10 seconds then turns off
•Turn off power and gas to the furnace
•Remove flame sensor from its bracket. Lightly clean the surface with fine emery cloth and replace.
•The problem may also lie in a bad ground or the the black and white wires being reversed (reversed polarity) at the junction box or outlet powering the furnace.
•The electronic ignition control module must ensure current flow through the flame sensor to ground and if the polarity is reversed in the circuit there is no voltage potential and the flame sensor does not work and closes the gas valve.
•If the black and white wires are connected correctly and the flame still drops out, then the issue may be a bad ground. Using a volt-ohm meter, measure between the white wire and the ground wire to be sure you have no voltage.
•If this does not work, replace the flame sensor. See Replacing an Electronic Flame Sensor.