We recently converted our Jaguar XJ8 to coil springs using the Strutmasters conversion and did not use the warning light module.
This is Strutmasters module number Jag1_CM-LM-REV A V1.0
Strutmasters claims this unit will turn off the Air Suspension Fault warning light associated with removing the Jaguar’s air springs when wired into the car’s suspension module. Instructions are included.
We ordered the kit specifically for our 2004 Jaguar XJ8. Strutmasters lists their kit as compatible with 2004-2010 Jaguar XJ8 vehicles, though I cannot verify this module will work on all years.