Sensors - TPS

TPS means Throttle Position Sensor or Throttle Position Switch.

Throttle Position Sensor is round shape, often with no adjustment slot and it has 4 pins show as below

Throttle Position Sensor has 3 pins and with adjustment slot

Throttle Position Sensor

There are four pins for the sensor, VC, E2, VTA and IDL

VC is the 5V power from the ECU, E2 is the sensor earth, VTA is the signal out to ECU and IDL is the idle control connect to battery. show as below

When the throttle open or close, the resistance between VC and VTA is changing, VC is 5V, so the voltage out off VTA is changing. More the throttle open, less resistance between VC and VTA, more resistance between VTA and E2, so the available voltage after VTA increased. When the throttle fully closed, IDL and E2 connected, and control the idle.

Test the Throttle Position Sensor

When throttle fully closed

When the throttle fully opened

When the throttle angle about 45 degree

When the throttle angle about 30 degree

When the throttle angle about 60 degree

When the throttle angle about 75 degree

Throttle Position Angle and Voltage Output

Throttle Position Angle	Voltage Output
0	0.58V
30	1.21V
45	2.20V
60	2.73V
75	3.09V
90	3.85V

The graph:

Throttle Position Switch

When the throttle shut, the resistance reading between E and IDL is 0.2R

When the throttle fully open, the resistance reading between E and PSW is 0.3R

When the throttle shut, the resistance reading between E and PSW is OL

When the throttle angle is 1 degree, the resistance reading between E and IDL is 0.2R

When the throttle angle is 75 degree, the resistance reading between E and PSW is 0.3R

The graph show below:

The TPS Switch internal operation:

 The switch internal circuit show as below:

When the throttle valve opening less than 1 degree, the E terminal connects to the Idle terminal, makes a circuit give the voltage reading to ECU through Idle. Between throttle valve opening about 1 degree to 75 degree. E does not connect to both Idle and PSW, so there are no voltage reading for both PSW and Idle to ECU. When the throttle valve opening more than 75 degree, E connect to the PSW, so there is voltage to ECU through PSW.