How to Connect a Scope Meter to a Throttle Sensor

Modern car engines use a variety of sensors to communicate temperatures, positions and fluid volumes. A throttle position sensor, or TPS, transmits the relative position of the throttle as the engine operates. The timing of an open or closed throttle helps the vehicle's on-board computer determine air-to-fuel mixture ratios. Connecting a scope meter, or voltmeter, to the throttle sensor helps troubleshoot a poorly timed car engine.

Instructions

1

Turn the car's ignition switch on. This allows electricity to flow through the throttle sensor.

2

Attach the voltmeter's negative lead to ground and the positive lead to the throttle sensor's reference wire. The throttle sensor has three wires protruding from its assembly. Each wire is labeled for easy troubleshooting.

3

Observe the voltmeter. The voltmeter's display should reflect 5 volts for a properly adjusted TPS.

4

Disconnect the voltmeter's positive lead from the reference wire and attach it to the TPS ground wire. The voltmeter should display a value of less than 0.5 volts, depending on the car model.

5

Detach the voltmeter's positive lead from the TPS ground wire and reattach it to the TPS input wire. The voltmeter should indicate a moving voltage between 1 and 5 volts. This voltage reading is a real-time observation of the throttle opening and closing and its effect on the voltage output.