Ford Ranger Owner's Manual page 257

The system is not a substitute for correct
tire maintenance.
You must maintain the correct tire
pressures, even if low tire pressure has not
illuminated the warning lamp.
The tire pressure monitoring system has a
system malfunction indicator to warn you
when the system is not operating correctly.
The malfunction indicator and low tire
pressure warning lamp have a combined
function. When the system detects a
malfunction, the warning lamp will flash
for approximately one minute and then
remain illuminated. This sequence will
occur every time you switch the ignition on
while the malfunction remains. The system
has detected a fault that requires service.
When the malfunction indicator is
illuminated, the system may not be able
to detect or signal low tire pressures. A
malfunction may occur for a variety of
reasons, including the installation of a
replacement tire or wheel that prevents
the system from functioning correctly.
Always check the tire pressure monitoring
system malfunction warning after
replacing one or more tires or wheels on
your vehicle. Make sure the replacement
tires or wheels allow the system to
continue to function correctly. See When
the Temporary Spare Tire is Installed
in this section.
How Temperature Affects the Tire
Pressures
Under normal driving conditions tire
pressures may increase by up to 0.3 bar
from a cold start situation.
Ranger (), EB3B-19G219-ZAB enAUS
Wheels and Tires
If the vehicle is stationary overnight and
the temperature is significantly lower than
the daytime temperature, tire pressures
may decrease by up to 0.2 bar when there
is a drop in the ambient temperature of
17°C or more. The system detects this
pressure decrease as being significantly
below the correct inflation pressure and
the warning lamp illuminates.
Changing Tires With a Tire
Pressure Monitoring System
E142549
You should always have tires serviced by
an authorized dealer.
Note: Each road wheel and tire is fitted with
a tire pressure sensor located inside the
wheel and tire assembly cavity. The pressure
sensor attaches to the valve stem. The tire
covers the pressure sensor and it is not
visible unless the tire is removed. Take care
when changing the tire to avoid damaging
the sensor.
Understanding the Tire Pressure
Monitoring System
You must maintain the correct tire
pressures, even if low tire pressure has not
illuminated the warning lamp.
The system measures the pressure in the
road tires and displays a warning lamp in
the instrument cluster when a low pressure
is detected. See Warning Lamps and
Indicators (page 61).
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