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· Registered
4,353 Posts
Discussion Starter · #1 ·
The TPS Throttle Position Sensor is located on the throttle body.

Product Technology Electronic device Auto part Electronics accessory

It has three pins, one is ground, one is 5.0 volt reference from the PCM, and one should return a variable voltage based upon the throttle position.

You can backprobe the TPS and it should move smoothely from 0.5 - 1.0 volt at idle, TO just less than 5.0 volts as you go from idle to wide open throttle. The transition must be so smoothe that you might miss it with a digital voltmeter and the only way to really check it is with an osicilloscope. IF you note dead spots, or fluctuations, it needs to be replaced.

A faulty TPS can give you a high idle, or a surging of the engine when the throttle is held at the same position.

· Registered
1,184 Posts
Poppy not everyone has an o-scope handy.I've been in the business for many years and I don't even have one.

i'm going to piggyback on your post with instructions from E-how.This should make it easy for everyone to perform.

Things You'll Need:

  • Voltmeter
  • Two pins
  1. Step 1
    Open the hood of your vehicle and locate the TPS sensor in the engine compartment. Its most common location is on the outside--to the right or left--of the throttle body or carburetor plate shaft. Here you will see a small black box with three wires coming out from its electrical connector.
  2. Step 2
    Unplug the TPS electrical connector. Turn on the ignition switch but do not start the engine. Using a voltmeter, probe the connector’s terminals coming from the computer side to test for supply voltage. Touch the negative lead to the connector’s terminal ground--most likely the black wire--and the meter’s positive or red lead to the connector’s terminal reference voltage wire, a blue or gray color wire. Your meter should read a steady 5.0 volts at the terminal. If you don’t receive this voltage reading, there is an open or short in the supply wire. Turn off the ignition switch and plug the electrical connector back to the TPS .
    Step 3
  3. Test the TPS for signal voltage to the computer. Insert a pin through the ground wire and another pin through the signal voltage wire and connect the voltmeter probes to the pins using alligator clips. Start the engine. As you manually open and close the throttle plate, watch the voltage readings at the meter. The voltage should gradually increase from 1 to 5 volts and back to 1 volt. If you see an erratic or no movement of voltage signal, replace the TPS sensor. Turn off the engine.
  4. Step 4
    Test the TPS sensor’s resistance. This is an alternate method to test TPS sensors equipped with a variable resistor. Unplug the TPS electrical connection. Set your multimeter to ohms. Connect the ohmmeter probes to the sensor’s supply and signal wire contacts. Manually open and close the throttle plate and watch the resistance reading at the meter. The resistance should gradually increase and decrease as you open and close the throttle plate. If there is an erratic resistance change, no change, or no resistance at all, replace the TPS.
  5. Step 5
    Adjust the TPS. Some sensors need to be adjusted from time to time. They are mounted with a couple of screws that allow the sensor to be rotated for adjustment. Loosen the mounting screws. With the ohmmeter connected as described in Step 4, rotate the sensor until you obtain the resistance specified in your vehicle service manual. Tighten the mounting screws and check the sensor’s resistance as described in Step 4
  6. Step 6 Plug in the TPS electrical connector, start your engine and test for performance.

· Registered
4,353 Posts
Discussion Starter · #3 · (Edited)
LOL... that's great! But where are the pictures?
Thanks BogHog, your addition was certainly an improvement!

What a minute... I don't think the engine needs to be running to check for a change in voltage. Does it?

I'm liking this site more and more each day :)
10 Posts
i always check with ohms on the digital ohmmeter

check the ohms as you slowly open the throttle

shoudl increase or decrease resistance very smoothly from closed to WOT

if it blinks anywhere or jumps alot somewhere at some point then its got a bad spot in it

· Registered
21 Posts
Hi guys,
I searched and found lots of info on TPS problems, but this is my situation: Replaced TPS and CEL went off, and MPG went up! BUT there is a definite miss going up hill. SO I check my TPS voltages and got 5V steady KOEOff, at the Voltage reference wire. But at the Signal voltage return wire, (KOEOn) I got 0.95 volts at idle, but could not get the voltage up about 2.1 volts when revving the engine to WOT.

These TPS are the adjustable kind. Should I try adjusting it? if so, which direction at idle? lower to 0.6 V or higher to 1.1 volts?

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