Q: Your vehicle is fitted with air-assisted hydraulic brakes. What fault would you suspect if the brake pedal becomes hard to press?
Correct answer:
The brake system has a loss of air pressure
Explanation
A fault in the air compressor could be the cause of a stiff brake pedal. There could also be a leaking connection allowing air to leak out of the compressed air system. Do not continue your journey until the fault has been fixed.