Throttle Position Sensor (TPS)

Throttle Position Sensor (Potentiometer)

The TPS is mounted on the throttle body and converst the throttle valve angle into an electrical signal, the signal voltage increases as the throttle opens.
The ECU uses throttle valve position information to know:


-   The mode of engine whether its idle part throttle or wide open throttle.
-   At Wide Open Throttle (WOT) AC emission controls are switched off.
-   Air-fuel ratio correction
-   Power increase correction
-   Fuel cut control

Explain its internal operation and why your voltage changes.

The volate supplied to TPS by the control module and change by internal variable resistor to output signal relative to throttle position, the typical TPS will have a high resistance at closed throttle position, that will steadily decrease as a throttle is opened. the signal produced by the TPS will be low voltage output that reaches maximum reference voltage.


At idle, voltage s approximately 0.6 – 0.9 volts on the signal wire. From this voltage the ECU knows the throttle plate is closed. At wide open throttle, signal voltage is approximately 3.5 – 4.5 volts.
Inside the TPS is a resistor and a wiper arm. The arm is always contracting the resistor. At the point of contact, the available voltage is the signal voltage and this indicates throttle valve position.

Now a connect a power supply to your sensor and test the voltage output at different throttle angles.

Throttle Angle	Voltage Output
0 Degree	5 V
20 Degree	4.12 V
40 Degree	3.13 V
60 Degree	2.30 V
80 Degree	1.87 V
90 Degree	0.75 V

Now plot your findings on a graph