Throttle position sensors

Throttle Position Sensors - The job of a TPS is to convert the throttle blade angle and throttle opening speed to an electrical signal that is sent to the PCM. The PCM then uses the electrical signal to determine engine load and adjust ignition timing.

Throttle position sensors - Jeep Wrangler YJ

Throttle position sensors on Jeep Wrangler YJ's are simple little sensors to test and replace if needed. Here I finally got around to changing the TPS. Here I give you step by step instructions of how to change the TPS and a quick test to make sure all is working correctly.

Where are TPS Sensors located?

Bolted to the side of the throttle body. Look where the throttle cable is connected to the throttle body. At the opposite end of that shaft is the TPS.

Will it trigger the check engine light if the sensor is faulty?

It may. I’ve seen cases where it didn’t. Jeep would just idle erratically or idle high. Or, possible dead spot as the throttle is opened. Run the DTC to see if it’s hiding the code and not illuminating the “Check Engine Light”. Or refer below or this video to test the sensor to determine if it’s faulty.

 Why does it fail?

Heat and vibration from being under the hood can eventually take its toll on the busy little sensor. Or, maybe it's because of fast heavy right foot actions :-).

 How do you test Throttle position sensors to see if they are bad?

To start out with you will need a simple tool called a multi-meter and a small paper clip.

  1. Test to make sure you have input voltage first. You do this by turning the key to the “On/Run” position.
  2. Put the black lead of your multi-meter to the Negative (-) side of your battery.
  3. Set you meter to test DC voltage. Get you a paper clip or a stiff bare wire small enough to go into the backside of the plug where the middle wire is located. Wire must be able to be inserted deep enough to make contact with the connector inside the plug with the connector still plugged to the TPS.
  4. With the red lead of the multi-meter lead check the output voltage of that middle wire that is being probed. With the throttle in the idle position you should have voltage greater than .2 volts but not too high (over 1 volt).
  5. Now open the throttle to the “wide open throttle” position, you should have less than 4.8 volts.
  6. In my first “How to test the throttle position sensor” video you can see that my idle voltage was way high. This caused the Jeep engine to idle a bit on the high side (~ 1200 rpm’s). It pinged a bit sometimes when it was under a load just as the throttle opened. I changed the TPS and it cured the high idle issue and occasional pinging on throttle “tip-in”.