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How to Test TPS With a Volt Ohm Meter

by Ryan Hotchkiss

A throttle position sensor --- TPS --- is an electrical resistor housed on the throttle body. The TPS feeds information to the engine control unit regarding the degree at which the throttle valve is open. Indications of a faulty TPS include engine stalling, lurching and sputtering; poor TPS performance starves the engine of fuel. While the TPS is a complex component of the engine, testing it is relatively simple and only takes a few minutes.

Locate the throttle body. Follow the fuel line to the housing mounted over the block of the engine. This is the throttle body. The device attached to the throttle body with the wires running to the engine control unit --- ECU --- is the throttle position sensor.

Identify the power, ground and signal wires on the TPS. Typically the ground is black, the power is red and the signal wire is a different color, blue for example. However, read the operator's manual to make certain. Rotate the multimeter dial to volts.

Check the reference voltage. This is the voltage running through the circuit between the TPS and the ECU. Touch the negative probe on the multimeter to the negative wire tab on the TPS and the positive probe to the positive tab. The multimeter will display around 5 volts if the TPS is working correctly.

Check signal voltage. Touch the positive probe to the signal wire tab and touch the ground probe to the frame of the car. If the TPS works correctly, the multimeter will display a reading of about 1/2 of a volt.

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