For 1990-2009 cars only
- Connect the trailer air lines, if equipped, to a known operating trailer.
- Block the wheels.
- Start the engine.
- Charge the system air pressure to the governor cut-out point.
- Apply the system park control, the trailer air supply, and the tractor park controls, if equipped.
- Stop the engine.
- Check that the brake lamps illuminate when you apply the foot brake or the trailer air brake control. If the switch does not function, replace the switch. Refer to Trailer Stop Lamp Switch Replacement .
- Check that the trailer air brake control and the foot brake operates the trailer service brakes when you apply the controls individually. If the switch does not function, replace the switch. Refer to Trailer Stop Lamp Switch Replacement .
- Remove the wheel blocks.
