CSX 8520/ Flashing Beacon

Saw the 8520 today at North Bergen, NJ, on the River Line. It has a flashing red beacon on the long hood mounted on top about 10 feet in back of the cab. Yes, it was working. The unit was in the middle of a 5-6 unit lashup heading north at 3:18 PM.

Are you sure it was red, not yellow? Was it located on the roof just about above where the "S" is on the pcture below? If so, that is a warning light for the APU. (Auto-start/stop feature).

And this one is of Seaboard heritage, judging from the nose-mounted headlights. (I don't think SBD used beacons)

the first order SBD SD50's had strobes mounted on the front corners of the cabs

you can still see the mounts on that picture above (above the number boards)

Some late order SD40-2's had them too

the light you are referring to is for the APU

As was mentioned, if the beacon was on the long hood it was part of the APU feature on the unit. APU automatically shuts down the unit if the unit is idle for an extended period of time at warmer temperatures and then can restart it if it is reset or controls activated......