I've got a 2000 International 4700 with hydraulic brakes, and the Brake Pressure Light is coming on after driving it for about an hour. The pressure really is low because the brake pedal sinks enough to trip the brake light switch. Neighbor suggested that this is usually the flow switch (on the master cylinder)... so I changed that... no such luck. Fluid seems to hold at a steady level. Brakes seem to function fine. (except the pedal lowering) Any suggestions? Thanks!!
Do you have vacuum assisted or hydraulic assisted brake system? Vacuum has the big canister Hydraulic has the pressure from the power steering pump amplify the pressure My older truck has the vacuum system and the pressure switch tells me there is a vacuum leak.... The pedal hanging low may be the key to solving this....