I am new to air brakes and air anything. Some things seem obvious, like electric air solenoids that trigger the face slapper. Other things, not so much. I'll post some pictures with descriptions.
Bus: 2002 Thomas HDX, Cat 3126B, Allison MD3060, Bendix ABS
Location: Between driver's seat and driver's wall
What is #2?
1 - Accessory air feed
2 - UNKNOWN?
3 - Electric air solenoid
4 - GND
5 - Signal wire for "DOOR OPEN - STOP"
6 - Air line to "face slapper" (flashing stop sign)