I have a 2011 F-250 that I purchased recently.
I noticed the 3rd light on the cab only had one light working, a cargo light, one of two.
I put in new bulbs, the other cargo lights then worked, but not the red brake light.
I noticed the socket appeared to have melted somewhat, as if it got hot at some point in time.
I purchased a new light bar online.
The change-out was straight forward, a mating plug, same mate.
I went and tried it out, the "red" light only comes on with the braking, is that the normal function?
I thought it was the same as the two main brake/running lights, yes....they light up when running, and brighten when braking, am I wrong on assuming this?

Thank you in advance!

 

Yes you are wrong. The rear lights have dual filament bulbs, the bright one hooks to the brake/turn, the dimmer filament hooks to the running light circuit.

The original 3rd brake light only has the brake function wired to it. It's actually a special dedicated wire going directly to the brake pedal switch, to avoid all the complication from the left and right turnsignals.

If the aftermarket light has the running light/brake light function, you could use it, but you would have run an extra wire from the running lights up into the b pillar and wire it in to your new light assembly.

 

Thank you.....

I was leaning that way, as the plug(s) female/male, were identical.
In hindsight it does seem to make more sense that having a light come on (the brake) when driving might get the follower attention a little better......all of a sudden a RED light comes on out of nowhere.
I just have to figger out how to wire in a siren, to get the full, "OH SHEET" effect