It depends on the car, some blink others are full either way the Led's remain on throughout the entirety of the session.

I have found that in the release build of Project Cars that in free practice on tracks where you do not start in the pits, the lights on the SRW-S1 seem to be flashing or on full blues and stay stuck on them. I think the cause is the fact that usually the free practice starts at full revs on the pit...