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Testing Sensors
Section
2
– Note: If test results are O.K. but a computer
trouble code indicates a bad sensor signal, the
wire between the sensor signal pin and the
computer may be open.
–
Testing is complete.
Problem exists (Bad sensor or wiring):
– TEST light position does not change during test.
–
Go to step 9 and continue testing to find cause.
Do all steps to avoid replacing a good sensor!
– Note: Sensor is defective if TEST light jumps
erratically when sensor GENTLY tapped with
lightweight tool.
9) Ignition key OFF.
10) Check for air intake problems.
• Air leaks - around MAF sensor, ductwork or
throttle body.
• Obstructions in air duct.
• Clogged air filter.
Repair as necessary, then retest. If no trouble
found, go to next step.
11) Check MAF sensor power circuit.
Keep sensor connected to vehicle wiring.
• YELLOW test lead to sensor POWER circuit.
Use backprobe adapter.
• BLACK test lead to good vehicle GROUND.
• RANGE on HIGH.
• FUNCTION on VOLTS.
• Ignition key ON.
Good power circuit:
Top (or next to top) TEST
light ON.
Go to next step.
Bad power circuit:
TEST light OFF or not in top
(or next to top) position.
Repair open or short in power circuit wiring, then
retest.
RANGE
HIGH
LOW
POWER OFF
FUNCTION
VOLTS
OHMS
FREQUENCY
TEST