Union Pacific's FEF-3 4-8-4

I have just recently purchased a Genesis UP FEF-3 and I am installing a Tsunami sound decoder. Does any body know what the front red light was used for, and did the FEF-3 use the same whistle as the Union Pacific challenger and Big Boy used.

If the train went in emergency the red light would come on.

No, the FEF’s did not share the big boy’s and challenger’s whistles. They sound similar though. I believe the FEF uses a Hancock 3 chime.

Thanks for the info.