Testing the throttle position switch

Testing the throttle position switch

If the Throttle Position Switch in the vehicle faulty , the vehicle shuld be not running correct.
The first test the condition of  contacts inside the switch , and should be checked for high resistance in both idle and full throttle position. To do this on a 3 pin TPS, place your earth ohmmeter lead onto the earth pin of the TPS and your positive lead onto either the IDL (Idle Circuit) pin, followed by the PSW (Power Switch), also known as WOT (Wide Open Throttle), whilst keeping your earth lead on the E (Earth) pin.

I had conect the ohm meter across the E and IDL pins and with the throttle shut, for checking the continuty .
Then the ohm meter across the E and PSW pins and check for continuty when the throttle is wide open .
IDL = OL
PSW = 0.5 0hms
The results at both PSW and IDL pins were 0.5Ω showing continuity. This result is what you would expect to find on a working TPS.
Explane the internal operation of this sensor and why  the resistance changes.

The Throttle Position Switch is operated by the throttle. When checking the TPS with an ohmmeter, readings of 0.5Ω or close to it shows continuity at each point. The resistance between idle and WOT varies depending on the car, the switch then signals the throttle opening to the ECU which then provides mixture corrections for both idle, off-idle and full throttle conditions.