Southern Pacific's Operation Of The Headlights On Their MP15AC's ??

The "headlights" on the left is a Mars light, (oscillating warning light) mounted horizontally rather than the usual vertically and normally activated by the engineer. 

The red light is also an oscillating warning light.  I'm not sure how it's applied in SP practice.

Rusty

SP Lighting Info  (This info is specifically about Geeps but I think it applies to SP units in general...)

SP was sold on the use of oscillating headlights, and required that the oscillating white light be used at all times when approaching any road crossing, as well as when moving on a main track.

Their officials must have been Nazis about enforcing it, as they would be stopped at a signal and still leave the oscillating headlight on.  On the Mojave Subdivision, we Santa Fe Engineers would dim our headlight when meeting any train, regardless if it was an SP or another Santa Fe, but not them -- they came blasting by with the Gyralite on bright.  Or you'd see an SP industry job with an MP15 running throughout the industrial park with the Gyralite on bright.

The red light was used the same as it was on other railroads which had them -- When it was displayed, any train approaching on an adjacent track had to stop.  It would automatically be displayed any time the air brakes were in Emergency or if a penalty brake application was in effect, to warn of the possibility of derailed equipment fouling adjacent tracks.