Goodman 2 stage ECM furnace. Here is the installation manual, service manual, and the spec sheet for this furnace.

Remember with venting, if you are within 5-10 feet of the maximum vent length, go to the 3" pipe. When we push the very limits of the vent table you will eventually get nuisance pressure switch trips and lockouts.

Inlet Gas Pressures:

Remember inlet gas pressure cannot exceed 14.0"wc, this is because the gas valve will lock up.

Manifold Gas Pressures:

Remember, even if the unit is going to run on natural gas, the gas valve has not been set properly. The "factory test" does not set gas pressure. So make sure to be checking and setting this with every install. 

CHECKING HOT SURFACE IGNITOR 120V Silicon Nitride Ignitor -

GMEC/GCEC96 use a 120V silicon nitride igniter for ignition. The normal operating temperature is approximately 2156°F - 2678°F.  At room temperature the ignitor ohm reading should be from 37-68 ohms. 7. Place unit in heating cycle, measure current draw of ignitor during preheat cycle. The steady state current at 120V is 0.37 to 0.68 amps. 8. After checking and/or replacing of hot surface ignitor, reinstall burner compartment door and verify proper unit operation.

Speed Tap Measurements:

The speed tap voltage is D.C. and can vary depending
on S2 DIP switch selection. The voltage reading from
any one of the speed taps is referenced between the
female COM terminal next to the speed taps on the control
board.

From COM to T1 or T2, 6-7 VDC when energized.
From COM to T3, 13-14 VDC when energized.
From COM to T4, 6-7 or 13-14 VDC

all depending on S2 settings.