Peterbilt brake light switch

[crane operator]

Anybody know peterbilts? The one I've been piddling with has no brake lights, on tractor or at trailer plug. It has this aluminum block on the cab floor, I'm assuming one of this mess of lines and switches, is a line from the brake applied off the treadle, for actuation of the pressure switch.

I'm just lazy, and didn't want to unhook all the air lines to see which one is pushing air when brake is applied, and wondered if anyone here happened to know which one is the brake light switch.

If I was real ambitious, I guess I could identify everything and use process of elimination. I should have air pressure low light, low air buzzer, power divider, brake switch, and I guess I'm forgetting something.

Anyways- if someone's been here before and said, "its third switch from the left on the right hand block" you would save me a bunch of work tomorrow.

Truck is a 1992 pete 379.

 

[pushbroom]

Brake light switch should be the second from the left, the larger diameter one with NC on it. The tall ones on the outside should be low air switches.

 

[crane operator]

Thanks, I had decided in the morning to use my tracer probe to back chase the brake wiring, rather than unhooking the hoses and finding air. You sure saved me some time, thanks.

 

[Truck Shop]

While your there you may as well replace the low air switches-notorious for going bad.

 

[heymccall]

Wouldn't a brake lamp switch be NO?
And the low air ones would be NC?