How To Test The TPS (1995-2000 4.0L OHV Ford Ranger And Mazda B4000)

By: Abraham Torres-Arredondo
Created: 16 June 2010
Updated: 16 March 2024
Articl Id: 111

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TPS TEST 2: Making Sure The TPS Is Receiving 5 Volts

Making Sure The TPS Is Receiving 5 Volts. How To Test The TPS (1995, 1996, 1997, 1998, 1999, 2000 4.0L V6 Ford Ranger And Mazda B4000)

The throttle position sensor (TPS) receives power from the fuel injection computer. This power is in the form of 5 Volts DC.

The terminal that delivers these 5 Volts to the TPS is the one labeled with the number 1 in the photo above.

In this test section you'll confirm if these 5 Volts are present or missing.

These are the test steps:

1
Select Volts DC mode on your multimeter.
2
Disconnect the TP sensor from its connector.
3
Probe the brown with white stripe (BRN/WHT) wire with the red multimeter test lead and an appropriate tool (like a wire-piercing probe).

The BRN/WHT wire connects to the female terminal labeled with the number 1 in the photo above.

NOTE: Be careful not to damage the female terminal.
4
Connect the black multimeter test lead to the negative (-) battery terminal.
5
When everything is set up, have a helper rotate the key to its ON position but don't start the engine.
6
The multimeter should display 4.5 to 5 Volts DC.

Let's take a look at what your test results mean:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct test result and it confirms that the TPS is receiving power.

Your next step is to make sure the TPS is getting Ground. Go to: TPS TEST 3: Making Sure The TPS Is Receiving Ground.

CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. This test result tells you that the TPS is not receiving power. Without these 5 Volts, the TPS will not function.

The two most likely reasons for this are:

An open-circuit problem in the wire between the TPS connector and the PCM connector.
The PCM may be fried (very very rare).

Altho' it's beyond the scope of this tutorial to test these two conditions, you have now eliminated the throttle position sensor (TPS) on your Ford 4.0L as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TPS TEST 3: Making Sure The TPS Is Receiving Ground

Making Sure The TPS Is Receiving Ground. How To Test The TPS (1995, 1996, 1997, 1998, 1999, 2000 4.0L V6 Ford Ranger And Mazda B4000)

If you've reached this point, you have:

Confirmed the TPS is not creating a throttle position signal (TPS TEST 1).
Confirmed the TPS is getting power (TPS TEST 2).

Your next and last test is to make sure that the terminal labeled with the number 3 is delivering Ground to the TPS.

CAUTION: The PCM is the one that provides this Ground internally, so be careful and don't accidentally or intentionally apply battery power (12 Volts) to this circuit. If you do, you'll fry the PCM.

OK, here are the test steps:

1
Grab your multimeter and select Volts DC mode on it.
2
Disconnect the connector from the TP sensor.
3
Probe the gray with red stripe (GRY/RED) wire with the black multimeter test lead and an appropriate tool (like a wire-piercing probe or a back-probe).

The GRY/RED wire connects to the female terminal labeled with the number 3 in the photo above.

NOTE: Be careful not to damage the female terminal.
4
Connect the red multimeter test lead to the positive (+) battery terminal.
5
When everything is set up, have a helper rotate the key to its ON position but don't start the engine.
6
The multimeter should display 10 to 12 Volts DC.

Let's take a look at what your test results mean:

CASE 1: The multimeter showed 10 to 12 Volts. This the correct test result and it confirms that the TPS is getting Ground.

You can also conclude that the PCM and the wire/circuit (that supply this Ground) are OK.

You can conclude that the TPS is bad and needs replacement if you have confirmed that:

The TPS voltage signal DOES NOT increase/decrease as you open/close the throttle plate (TPS TEST 1).
The TPS has power in the form of 5 Volts DC (TPS TEST 2).
The TPS has Ground (TPS TEST 3).

If you need to replace the TPS, check out the following section: Where To Buy The TPS And Save.

CASE 2: The multimeter DID NOT show 10 to 12 Volts. This tells you that the TPS is not getting Ground.

This is usually due to a problem with either the PCM (internal fault/problem) or an open-circuit problem in the wire between the TPS and the PCM itself.

Altho' testing these two conditions are beyond the scope of this tutorial, you have now eliminated the throttle position sensor (TPS) on your Ford vehicle as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TPS Code Won't Go Away

Quite a few things, other than a bad TPS, can cause the PCM to illuminate the check engine light with a TPS diagnostic trouble code. If this is happening in your case, take a look at the following testing suggestions:

The throttle plate's idle-stop screw's factory adjustment has been altered so that the engine could be idled up and mask a miss/misfire and/or rough idle. This increases the TP sensor's signal to the PCM. The PCM doesn't like it and lights up the check engine light (CEL).
The throttle cable is binding and causing the throttle plate to not fully close.
- This can be verified by simply having someone inside the vehicle pushing the accelerator pedal to the floor and releasing it, with the engine OFF, while you visually check that the throttle plate and cable are not getting stuck somewhere in their travel.
The TPS is failing intermittently. Which means that it works fine most of the time, but every now and then it doesn't:
- I've found that the best way to test these intermittent problems is to road-test the vehicle with the multimeter hooked up to the TP signal wire with a long wire so that I can comfortably observe the signal going up and down as I or someone else drives.
The TP sensor's connector is bad, usually the locking tab is broken and the connector has worked itself loose, causing an intermittent false connection.