Primary and Secondary Air Pressure Gauges
p4 dm 03.05.000
Physical instruments are listed here in alphabetical order. Some are optional and therefore not found in every vehicle. Digital instruments and gauges are described in their ICU section.
Warning: If air pressure falls below minimum pressure,
the braking ability of the vehicle will be limited. Slow the vehicle
down and bring it to a gradual stop. Do not attempt to move the vehicle
until air pressure has risen above the minimum level. Moving a vehicle
without adequate braking power could cause an accident resulting in
property damage, personal injury, or death.
Air pressure gauges register the pressure in the primary and secondary air systems. See Fig.. Normal pressure, with the engine running, is 123 to 140 psi (850 to 970 kPa) in both systems.
Fig. 1, Analog Combined Application Air Pressure Gauge - ICUC
Note: The low-air warning buzzer only works when the park brake
is released. The low-air warning buzzer is silenced when the park
brake is set.
If air pressure drops below approximately 70 psi (483 kPa), a warning light illuminates and the driver display shows a warning. A low-air warning buzzer also sounds if the park brake is not set.
Note: If the pressure in both air systems drops
below 70 psi, the parking brakes will drag or apply.
Note: