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OXYGEN
Heating Element Test
• Do this test if sensor has a heating element (3 or 4 wire connector).
• If sensor has 1 or 2 wire connector, do not do this test. Go directly to On-Car
Test (page 2-22).
Warning: Observe all safety precautions (see page ii) if testing sensor on vehicle.
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) Connect test leads.
• YELLOW to either sensor HEATER pin.
• BLACK to remaining sensor HEATER pin.
5) Verify test clips make good contact and do not touch each
other.
Make sure unused clips are not touching anything.
6) Set RANGE switch to HIGH.
7) Set FUNCTION switch to OHMS.
8) Observe TEST light for test results.
• Good Heater:
TEST light OFF (low resistance).
• Bad Heater:
TEST light ON in any position (resistance too
high, or open circuit).
9) Heating Element test is complete.
• Set RANGE switch to POWER OFF and remove all test leads.
• Go to On-Car Test.
RANGE
HIGH
LOW
POWER OFF
FUNCTION
VOLTS
OHMS
FREQUENCY
TEST