Subaru 2002 Impreza Service Manual page 451

OUTSIDE AIR TEMPERATURE DISPLAY
InstrumentatiotdDriver Info
2. Outside Air Temperature Display
A: CONSTRUCTION
The outside air temperature display system consists of an ambient sensor, the CUSTOM CPU and
a liquid crystal display installed in the combination meter. The ambient sensor detects the outside
air temperature using the built-in thermistor which varies its resistance according to change in am-
bient temperature, and sends signals to the CUSTOM CPU.
As soon as the ignition switch is turned ON, the CUSTOM CPU compares the temperature data
sent from the ambient sensor with the one that was stored in its memory when the ignition switch
was turned OFF last time and it causes the lower of the temperatures to be displayed. However,
if 60 minutes or more time has passed between the last turning OFF and the next turning ON of
the ignition switch, the temperature that is displayed is a sensor-provided temperature.
When the vehicle is running slowly, the heat released from the engine compartment raises the tem-
perature of the air around the ambient sensor and this affects the temperature data the sensor
sends to the CUSTOM CPU. The CPU then makes a special control using the vehicle speed data,
i.e., when the vehicle is running at a speed slower than 10 km/h, the CPU uses the temperature
that was detected during the most recent vehicle's movement at a speed exceeding 10 km/h rather
than a temperature currently being provided by the ambient sensor.
NF0140
(1 ) Ambient sensor
(2) Outside air temperature display
IDI-I 4