Stoplamp Switch Mechanical Test, Service and Trailer Air Brake
- Connect the trailer air lines, if equipped, to a known operating
trailer.
- Block the vehicle wheels.
- Start the engine.
- Charge the air system to the governor cut-out point.
- Apply the system park control, the trailer air supply, and the
tractor park controls, if equipped.
- Turn the engine to OFF.
- Ensure the following:
| • | The brake lamps should illuminate when either the foot brake or
the trailer air brake control is applied. |
| • | The trailer air brake control and the foot brake should operate
the trailer service brakes when applied individually. |
| • | If either of these switches does not function, replace the faulty
stoplamp switch. |
