[bestgenman]

David,  the solenoid colors are: black = ground,  red = hold in,  white = pull in.   The FE is nothing more than a normally open switch held closed by the pressure inside.  It can be in series with either solenoid black or solenoid red, one or the other.   I’m not sure if this answers your specific question.   There are many others on the site that have explored the wiring and several threads also.

The FE switch also should have a separate set of contacts not connected to the engine wiring for the pilot lamp in the cockpit to indicate the FE still has pressure.