Generac 22 KW 
Model# RGO2224ANAX
Serial# 3004580036

Thomson ATS
Model# TS912A0200A
Serial# MW-023117-001

All generator functions work properly except exerciser. Generator will not start and exercise. Switch is being used for all functions and not controller on generator. What should I check when I go and check? I have never installed residential generator on a Thomson ATS. Thanks 
Brian Baughman
The liquid-cooled generators do not exercise when re-programmed for 2-wire start.  Typically, exercise is controlled by the 2-wire start ATS, so it gets disabled in the generator.   You could add a programmable timeclock to simulate a weekly exercise.
The Thomson ATS has an exercise mode built-in. 
IIRC you can select weekly, bi-weekly or monthly, and with or without load using jumpers on the board. 

I always run my exercise under load to make sure it gets the oil up to temp.  Also, running a diesel with no load can cause cylinder glazing.