32
range to get a more accurate
reading.
For all other temperature sen-
sors:
• Start engine and let idle until
upper radiator hose is warm.
• Turn ignition key OFF.
• Disconnect sensor wiring har-
ness and reconnect multimeter
test leads.
• View and record reading on
display.
12.Test Results.
Good Sensor:
• Temperature sensors HOT re-
sistance is at least 300Ω less
than its COLD resistance.
• The key point is that the COLD
resistance decreases with in-
creasing temperature.
Bad Sensor:
• There is no change between
the temperature sensors HOT
resistance from the COLD re-
sistance.
• The temperature sensor is an
open or a short circuit.
Position Type
Sensors
Position sensors are potentiometers
or a type of variable resistor. They
are used by the computer to deter-
mine position and direction of move-
ment of a mechanical device. Typi-
cal position sensor applications are
throttle position sensors, EGR valve
position sensors, and vane air flow
sensors.
Test Procedure (see Fig. 29):
1. Insert BLACK test lead into
COM test lead jack.
2. Insert RED test lead into
test lead jack.
3. Disconnect wiring harness
from sensor.
4. Connect Test Leads.
• Connect RED test lead to sen-
sor POWER pin.
• Connect BLACK test lead to
sensor GROUND pin.
• Refer to vehicle service manual
for location of sensor POWER
and GROUND pins.
5. Turn multimeter rotary switch
to 20K
Ω range.
Fig. 29
Typical Toyota Throttle
Position Sensor
Red
Black
POWER GROUND
SIGNAL IDLE SWITCH
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