freightliner BUSINESS CLASS M2 Driver Manual page 15

Instruments
Primary and Secondary Air Pressure
Gauges
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 pres-
sure 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, as shown in
the pressure in the primary and secondary air sys-
tems. The gauges are labeled for the A or B reser-
voir. Normal pressure with the engine running is 100
to 120 psi (689 to 827 kPa) in both systems.
05/14/2001
Fig. 3.14, Air Pressure Gauge (reservoir A shown)
A low-air-pressure warning light and audible alert,
connected to both the primary and secondary sys-
tems, activate when air pressure in either system
drops below approximately 70 psi (483 kPa).
When the engine is started, the warning light and
audible warning remain on until air pressure in both
systems exceeds minimum pressure.
Speedometer
Three speedometer options are available. The U.S.
version of the speedometer registers speed in both
miles per hour (mph) and kilometers per hour (km/h),
with mph in larger numbers. The metric version of
the speedometer face reverses this arrangement,
with km/h in larger numbers. The metric-only version
shows km/h exclusively.
3.13
Fig. 3.14, register
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Tachometer
The tachometer indicates engine speed in revolutions
per minute (rpm) and serves as a guide for shifting
the transmission and keeping the engine in the ap-
propriate rpm range. For low idle and rated rpm, see
the engine identification plate.
Transmission Fluid Temperature
Gauge
The transmission fluid temperature gauge, shown in
Fig. 3.15, measures the transmission lubricant oper-
ating temperature. Temperatures vary by application,
but the transmission fluid temperature gauge reading
should not exceed 250°F (121°C).
200
F
125
10/30/2001
Fig. 3.15, Transmission Fluid Temperature Gauge
NOTICE
A sudden increase in transmission fluid tempera-
ture that is not caused by a load increase may
indicate mechanical failure. Bring the vehicle to a
safe stop and investigate the cause to prevent
further damage. Do not operate the vehicle until
the cause has been determined and corrected.
Under heavy loads, such as when climbing steep
grades, temperatures that exceed the normal oil tem-
perature range for a short period are not unusual. If
the temperature returns to normal when the load de-
creases, there is no problem.
Turbocharger Boost Pressure Gauge
A turbocharger boost pressure gauge indicates the
pressure in the intake manifold, in excess of atmos-
pheric pressure, being created by the turbocharger.
275
350
TRANS
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