Ignition module and ignition sensor as per 03-07 Service Manuals, are in fact the same component. The folks at Harley-Davidson Publications/Documents division published all the XB-XL-XR manuals, so they tend to intertwine nomenclature. It is the component located behind the cover plate on the nose end of the cam cover. It simply signals the ECM as to what position the crankshaft is in relative to required ignition parameters.
Intermittent loss-of-spark causes:
Failing coil---------most common
Failing CPS--------fairly common
Failing plug high-tension wires----most common
Coil feed wiring harness chafed thru---least common
Failing kill switch---------------least common
Failing ignition switch----------least common
CPS-do heat test
Coil--do OHMS test
Plug wires---do OHMS test
All else---do visual
You're welcome.