- Block the wheels.
- Test the vehicle dual air pressure gauge with the test gauge.
- Install the test air pressure gauge in the valve delivery line.
- Start the engine.
- Charge the system air pressure to the governor cut-out point.
- Move the trailer brake control valve lever to the full OFF position.
- Check that the test air pressure gauge indicates zero air pressure.
- Repair or replace the control valve (5) if the air pressure does not indicate zero.
- Move the trailer brake control valve lever to the full ON position.
- Check that the test air pressure gauge indicates the same air pressure as the dual air pressure gauge.
• | If the pressure is not the same, adjust the valve (5). Refer to Valve Adjustment. |
• | If the valve (5) does not deliver full pressure after the adjustment, replace the valve (5). |
- Move the trailer brake control valve lever to several intermediate positions.
- Drain the air system reservoirs. Refer to
Air Brake Reservoir Draining
.
- Remove the test air pressure gauge.
- Check the operation of the brakes.
- Remove the wheel blocks.