G'day
Engine run ups are not really my world, but colour vision defects don't generally affect the interpretation of simple red or green lights/indicators. The degree of greeness or redness maybe, but that is not usually important.
My understanding is that only a very small subset of colour defectives have a problem with telling red from green, despite it being commonly called red/green colour blindness.
Ever wonder why not many colour defective people drive through red lights?
Yes I am colour defective, and on my way to a PPL in OZ.
Cheers
Murray