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Testing Sensors
Section
2
Off-Car Test
Warning: This test involves use of an open flame from a propane torch.
Observe all safety precautions for torch operation. Do not use near flammable
material or gases.
1) Verify ignition key is OFF.
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
disconnecting wiring harness.
4) Remove sensor.
5) Firmly grasp sensor with a pair of locking pliers.
6) Connect test leads
• YELLOW to sensor SIGNAL pin.
• BLACK to sensor GROUND.
7) Verify test clips make good contact and do not
touch each other.
Make sure unused clips are not touching anything.
8) Set RANGE switch to LOW.
9) Set FUNCTION switch to VOLTS.
10) Light torch - Heat sensor tip - Observe RICH/
LEAN lights.
• Thoroughly heat sensor tip until tip is as hot as
possible, but not “glowing”. See Fig. 1.
• The sensor tip must be very hot to operate! (349(C,
660(F)
• The LEAN or RICH light should be ON. If both lights
are off, the sensor is defective.
FUNCTION
VOLTS
OHMS
FREQUENCY
RANGE
HIGH
LOW
POWER OFF