How to Troubleshoot a Fiero TPS

The throttle position sensor, or TPS, on the Pontiac Fiero is located on the throttle body. Should the TPS malfunction, depending on the year Fiero, you may have to remove the throttle body, as some models have the screws welded in. The connector may be oblong or round. It has three wires attached to it: the PCM positive, which is gray; the PCM negative, which is black or orange; and the TP signal wire, which is dark blue.

Instructions

1

Insert the pin or needle into the signal wire. Attach the voltmeter's red lead to the pin. Attach the black lead to a known good ground. A known good ground is any bare metal that is not chrome or aluminum, or the negative battery terminal, if the lead will reach.

2

Turn the key on, but do not start the vehicle. The voltmeter or power graphing meter should read less than 1 volt. If not, continue with step 3.

3

Move the pin or needle to the PCM negative wire. Attach the red lead from the voltmeter to the pin. Leave the black lead on the known good ground. Turn the key on, but leave the engine off. Voltage should be less than 100 mV. If the voltage is correct, continue with step 4.

4

Disconnect the wiring harness connector from the throttle position sensor. Probe the PCM positive wire on the wiring harness end with the red lead and leave the black lead on the known good ground. You should have 5 volts. If not, the problem is in the wiring or the computer. If you have 5 volts, the problem is with the throttle position sensor. Replace the throttle position sensor.

5

Remove the pin from the wire and turn the key off.