"Watchguard -- burners failed to ignite"

Hi guys,

Any help I can get here I would greatly appreciate it.

I have a Lennox G40DF(X) furnace which I just personally replaced the Draft Induce Blower (Lennox Furnace Draft Inducer Blower (7002-2975, 313L5501) Fasco # A200). The reason I replaced it was due to a horrible grinding sound the fan would make every time it fired up. Replaced it and all sounds well now.

Problem is that now I get this "Watchguard -- burners failed to ignite" message every few cycles and the system shuts down on me with this error. I have to then manually shut the system down and re-start it and then it works fine again for a few cycles and then the same happens.

I am thinking that maybe I wired something incorrectly when I installed the new blower. The new blower came with a new Combustion Air Proving Switch attached to it. I accidentally unplugged the two purple wires attached to the old Proving Switch but I failed to mark them on which one connects to what connector. So maybe a crossed the two purple wires and this is why this error message is popping up all the time. The two purple wires are exactly the same, so that made things a little more difficult to determine which is which. So I followed each wire to where it connects to and one goes to the circuit board on the furnace and the other goes to the Limit Control near the burners.

Could this be the cause of my problem? I realize that I can just re-connect the wires the other way and see if that works, but I guess I'M AFRAID TO BLOW UP THE HOUSE by using trial and error.

Can anyone help me out on this?

There are two connectors on this proving switch (left and right side) and I have a wire coming from the circuit board and the other from the Limit Control. Where should I connect each wire.

Thanks for any help