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How to Fix Throttle Position Sensor on 1985 Pontiac Fiero

The throttle position sensor in your 1985 Pontiac Fiero is a variable resistor, also called a potentiometer, that is attached to the end of the throttle shaft. As the the throttle pedal is pushed and the throttle shaft rotates, the resistance in the potentiometer decreases, allowing more of the 5-volt reference signal to return to the onboard computer. The computer uses this varying voltage, along with input from other sensors, to calculate engine load and to control the fuel and ignition systems for best performance and fuel economy.

Tools Used: Digital volt/ohm meter, Torx driver set, Straight pin

Fix Throttle Position Sensor

Turn the ignition key to the "OFF" position. Lift the hood release located under the right side of the dash and raise the hood. On the four-cylinder engine, remove the air cleaner, located on top of the engine, by unscrewing the wing nut on the air cleaner and lifting it off the engine. The TPS sensor is located on the throttle body on the opposite side from the throttle cables. On the V-6 engine, the TPS is located on the front of the throttle body, facing you, and no parts need to be removed to gain access to it.

Lift the locking tab on the electrical connector at the base of the TPS and pull the connector from the sensor. Unscrew the two small screws that attach the TPS to the front of the throttle body, using a T-15 torx driver. Slip the sensor off the throttle body and lay it aside.

Rotate the new sensor clockwise slightly so that the metal tap on the back of it hooks onto the end of the throttle shaft protruding from the throttle body's TPS cavity. Insert the sensor into the cavity and rotate it counterclockwise until the screw holes in the sensor line up with the screw holes in the throttle body. Install the screws and leave them slightly loose. Plug the electrical connector into the TPS sensor.

Insert a straight pin into the back of the electrical connector along the blue colored wire until you feel it contact the terminal in the connector. Clip the red (power) lead of the digital volt/ohm meter to the straight pin. Clip the black (ground) lead of the meter to a good engine ground.

Set the meter for "volts d/c" and turn the ignition key to the "ON" position. Rotate the sensor until the voltage on the meter reads .5 volts. Tighten the mounting screws. It is common for the TPS to shift slightly when the screws are tightened. Readjust if necessary until the meter reading is at .5 volts with the screws tightened.

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