Actron AutoAnalyzer CP7665 - Manual (Page 29)

29
Red
Black
Hair Dryer
Typical
Intake Air
Temperature
Sensor
3. Insert RED test lead into
test lead jack.
4. Disconnect wiring harness
from sensor.
5. If testing Intake Air Tempera-
ture Sensor - Remove it from
vehicle.
All other temperature sensors
can remain on vehicle for test-
ing.
6. Connect RED test lead to ei-
ther sensor pin.
7. Connect BLACK test lead to
remaining sensor pin.
8. Turn multimeter rotary switch
to desired OHM range.
If the approximate resistance is
unknown, start at the largest OHM
range and decrease to the appro-
priate range as required. (See
Setting the Range on page 6.)
9. View and record reading on
display.
10. Disconnect multimeter test
leads from sensor and recon-
nect sensor wiring.
This step does not apply to in-
take air temperature sensors. For
intake air temperature sensors,
leave multimeter test leads still
connected to sensor.
11. Heat up sensor.
If testing Intake Air Temperature
Sensor:
• To heat up sensor dip sensor
tip into boiling water, or...
• Heat tip with a lighter if sensor
tip is metal or a hair dryer if
sensor tip is plastic.
• View and record smallest read-
ing on display as sensor is
heated.
• You may need to decrease the
• Oxygen Sensor output signal
did not change when exposed
to a rich and lean condition.
• Oxygen sensor output voltage
takes longer than 3 seconds
to switch from a rich to a lean
condition.
Temperature Type
Sensors
A temperature sensor is a thermistor
or a resistor whose resistance
changes with temperature. The hot-
ter the sensor gets, the lower the
resistance becomes. Typical ther-
mistor applications are engine cool-
ant sensors, intake air temperature
sensors, transmission fluid tempera-
ture sensors, and oil temperature
sensors.
Test Procedure (see Fig. 28):
Fig. 28
1. If engine is HOT let it COOL
down before proceeding.
Make sure all engine and trans-
mission fluids are at outside air
temperature before proceeding
with this test!
2. Insert BLACK test lead into
COM test lead jack.