Temperature Sensor Test Procedure
Use this procedure for testing all engine coolant or inlet air temperature sensors.
Exceptions:
• Certain Toyota, Nissan and Ford engines using vane airflow sensors have the
air temperature sensor built into the vane airflow assembly. Refer to page 2-40
for testing.
• GM 1988 2.8L Mass Airflow Sensor (5 pin only) also has a built-in air tempera-
ture sensor. Use same test procedure as for vane airflow temperature sensor.
Refer to page 2-34 for testing.
Sensor may be tested on or off vehicle.
Warning: On-car testing involves running engine. Observe all safety precautions
(see page ii). Work in well ventilated area.
2-4
Testing Sensors
1) Verify ignition key is OFF.
Allow engine to cool to outside temperature before testing.
2) Check Tester battery
Refer to page 1-4. Set RANGE switch to POWER OFF
when done.
3) Disconnect wiring harness from sensor - Inspect for
damage.
Some vehicles use a metal snap ring to secure wiring
harness to sensor. Remove this snap ring before discon-
necting wiring harness.
4) Off-Car testing only: Remove sensor.
Be careful of coolant spillage from mounting hole if
removing engine temperature sensor.
5) Connect test leads.
• YELLOW to
either sensor pin.
• BLACK to remaining sensor pin.
Yellow
Black
Section
2
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