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Daily inspection test
Exterior Items

1. Slow air pressure build-up rate

You must know the proper method for testing the air pressure build-up rate, and that a vehicle has this minor defect when it takes longer than two minutes for air pressure to build up from 85 to 100 psi.


    • Ensure the trailer supply valve is closed (pulled out when equipped).
    • Release the parking brake.
    • Pump brakes to reduce air pressure to 552 kPa (80 psi or less).
    • Maintain engine speed of 600 to 900 RPM.
    • Note time for pressure to rise from 587 to 690 kPa (85 to 100 psi) while maintaining specified engine speed.
    • Note the build-up time and tell the examiner.