My car was giving voltage too high on TPS input. I replaced the TPS and still have same problem. Any suggestions on what it might be? I traced wiring back to wiring loom, but didn't go any further. How do I test the voltage at the TPS?

Thanks!

 

It would be a help if we knew what year and which engine you have...

 

That makes sense...

86, 305 TPI

 

Throttle Position Sensor (TPS)

Tools needed:
1. Digital Volt-Ohm-Meter (VOM)
2. Breakout jumper wires or probes (make your own)
3. AutoXray, Diacom, or similar scanner will replace the VOM and jumper wires.

Turn on ignition, but don't start the engine.

If you are using a diagnostic scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.07 VDC.

If you are using a VOM, connect the meter leads to the TPS electrical connector terminals ‘A' and ‘B'. Your car should have a black wire on terminal "A" providing ground, a gray wire on terminal "C" supplying 5.0 VDC from the ECM, and a blue wire on terminal "B" sending the variable signal back to the ECM.
Turn on the ignition to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.

After achieving the desired setting, turn off the ignition switch. Remove all jumpers or the scanner and reconnect the TPS connector as required.

If the voltage cannot be set to the specification, check the TPS reference voltage across terminals "A" and "C". The ECM should be supplying 5.0 VDC across those terminals. If the voltage is out of that range, there may be a wiring problem between the ECM and TPS, a problem with ECM ground connections or engine ground connections, or an internal ECM problem. To check for ground problems, measure the voltage from terminal "C" to a good ground or negative battery terminal If the reading is around 5.0 VDC, the ground wire or connections may be a problem.

 

I will give this a shot! Thank you!