Actron CP9087, Service Manual

Page: 14 / 88

2-6
Testing Sensors
Section 2
TYPICAL THROTTLE POSITION SENSORS
Throttle Position Sensor
The throttle position sensor is a
potentiometer - a type of variable
resistor (similar to a dashboard
dimmer control). These sensors come
in a wide variety of styles - some with
connectors at the end of a short wire
“pigtail”. The computer supplies power
and ground to the sensor. The sensor has an element which is
turned (rotary type) or pushed (linear type). When the sensor is
mounted on the engine, the element is linked to the throttle so
they move together. The sensor sends a voltage signal back to
the computer indicating element (and thus throttle) position. The
voltage signal increases when the throttle opens and operates
the sensor element. Throttle position sensors on Asian vehicles
may also include one or two throttle position switches.
Throttle Position Switch
This is one or two switches usually built into a single housing
(often resembling a throttle position sensor). Movement of the
throttle linkage operates the throttle switches. The switches are
wired to the computer. The computer usually supplies an
ground connection to one side of each switch.
• The idle position switch is closed (or open - depends upon
vehicle) when the throttle is resting. The switch operates
when the throttle is opened (by any amount) and no longer in
the idle position.
What
is It?
SIGNAL
VOLTAGE
ROTATION
HIGH
LOW
MAX. MIN.