The Ranger TPS Sensor in your Ford is a three pin unit that’s connected to your throttle shaft. As your Ford throttle body opens this sensor relays the position of your throttle blade to your Ranger computer. The engine computer uses this data to deliver the right amount of fuel to your 3.0 liter V6 Ranger engine.
Problems with inconsistent throttle response or an engine that revs on it’s own are just two of the more common issues with your Ranger TPS Sensor. Of course one of the most obvious indicators of a throttle sensor error is your check engine light turning on in your Ford instrument cluster.
When you see that dreaded yellow check engine light, you’ll need a OBDII scan tool to find out what the problem really is. After you’ve retrieved the OBDII trouble code in question, you will know what the issue with your throttle sensor really is. These OBDII codes are alphanumberic five digit codes like P0120: Throttle Position Sensor Circuit or P0121: Throttle Position Sensor Circuit error.
Today I’ll be showing you how to test your Ranger TPS Sensor in a 1998 Ford truck with a 3.0 liter V6 engine in it. In order to complete this test you’ll need to use a digital multimeter to read the voltage at the ENGINE harness.
Testing the Ranger TPS Sensor for Power
To begin this guide, open your Ranger hood and locate the throttle sensor. The TPS sensor for your 3.0 liter Ford is mounted to your throttle body and is connected by way of a three pin connector. Turn your Ranger ignition to the “ON” position so that power is being sent to your engine sensors.
Now disconnect the Ranger TPS Sensor and remember you will be testing the ENGINE side of the harness. Unplug your throttle sensor and the wire you will be checking first is the one that leads to PIN C. When in doubt about the pins in question you can also look down the connector as the letters are also stamped into the throttle sensor.
The wire that leads to PIN C is a BROWN wire with a WHITE stripe in it. There should be 5 volts of DC power here with the ignition turned to “ON”
If you have power at this wire, the next signal to check for is ground. This is the wire that leads to PIN A. This wire is a GRAY wire with a RED stripe in it.
Remember that you are testing the ENGINE harness side of your Ranger TPS Sensor. When testing the female connector, never force the multimeter leads into the connector. Doing so may damage the metal clips that are inside the connector, which could lead to inconsistent terminals contact.
Testing the Ranger TPS Sensor Signal
The last part of our test requires you to plug your Ranger TPS sensor back into the unit. Once you have the wiring connector plugged in, you must test the wire at PIN B. This wire is a GRAY wire with a WHITE stripe in it.
Reconnect your TPS sensor and pierce wire B with your multimeter lead. To be sure make sure that the black lead of your multimeter is at the negative terminal of your Ranger battery.
You do not need to start your 3.0 liter Ford engine. Keep the ignition turned to the “ON” position and measure the voltage at wire B. This voltage should read between .3 to .9 volts of DC signal. Remember this is with your throttle plate in the closed position. Now manually open your throttle body and you’ll see that the voltage will slowly scale upwards as you open it.
The voltage should stop between 3.9 and 4.6 volts of DC signal. This represents your throttle at the fully open position. This is also known as Wide Open Throttle or WOT in your 3.0 liter Ford throttle body.
If your Ford Ranger TPS sensor does not respond with these values, you need a replacement throttle sensor. Once you’ve removed and replaced the throttle position sensor in your 3.0 liter Ford engine, don’t forget to calibrate the sensor. You will need to repeat the last leg of our How To Test to properly calibrate the Ranger TPS sensor.
Have any questions about this How To guide? Leave us a comment below and let us know!
