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78 Instruments and Controls
J — Master Warning Telltale
The Master Warning Telltale and buzzer
alerts of a dangerous situation. Air pres-
sure is low and the remaining air volume
may not be enough for repeated braking.
The emergency brakes may engage,
causing a wheel lock-up, loss of vehicle
control and become a hazard to follow-
ing vehicles. Bring the vehicle to a
controled stop. Failure to follow these
precautions can result in loss of braking
control and serious personal injury or
death can occur as a result of a vehicle
accident.
This will light up when either front or rear
air brake system pressure drops below 60
psi (410 kPa) or lower. The buzzer will
also sound when the telltale lights up.
When the pressure goes above 60 psi in
both front and rear brake circuits, the tell-
tale will automatically go out.
Air brake system pressure should be be-
tween 90 to 135 psi (620 to 930 kPa) for
normal operation. The master warning tell-
tale comes on and the buzzer sounds when
air pressure has dropped to 60 psi or lower.
If the air pressure is allowed to drop below
30 to 40 psi (200 to 275 kPa) in both
systems, the parking spring brakes will au-
tomatically engage and stop the vehicle.
When the master warning telltale comes on
and before the parking spring brakes en-
gage, stop the vehicle in a controlled
manner at an off-road location so as not to
be a hazard to other vehicles on the road.
Refer to page 224 for more information
about the brakes.
W3000638