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Sensor Types
Testing Sensors
Section
2
1-Wire: Single wire goes to sensor SIGNAL.
Sensor housing is connected to sensor GROUND.
2-Wire: One wire goes to sensor SIGNAL. Second
wire goes to sensor GROUND. Refer to vehicle
service manual for wire identification. (Sensor wire
is often black.)
3-Wire: Two wires (often the same color) go to the
sensor heating element. Third wire (different color
from the others) goes to sensor SIGNAL. Sensor
housing is connected to sensor GROUND.
4-Wire: Two wires (often the same color) go to the
sensor heating element. Third wire goes to sensor
SIGNAL. Fourth wire goes to sensor GROUND.
Refer to vehicle service manual for wire identifica-
tion. (Signal wire is often black.)