How To Test The TPS (1993-1995 4.0L Grand Cherokee)

TEST 2: Verifying TPS Has Power

The VIO/WHT (violet w/ white stripe) wire is the one that feeds power (5 Volts DC) to the throttle position sensor (TPS).

This power comes from the PCM. In other words, the other end of the VIO/WHT wire connects directly to your Jeep Grand Cherokee's powertrain control module (PCM).

The VIO/WHT wire is the one that connects to terminal #3 in the photo above.

NOTE: You can test for these 5 Volts DC with the TP sensor connected or disconnected to the TPS. I personally prefer to do this test with the TP sensor's connector unplugged.

This is what you'll need to do:

1. 1

   Place your multimeter's dial in Volts DC mode.

2. 2

   Disconnect the throtle position sensor from its connector.

3. 4

   Turn the key to the ON position but don't crank or start the engine.

4. 5

   Connect the black multimeter test lead to the negative (-) battery terminal.

5. 6

   Gently probe the terminal labled with the number 3 with the red multimeter test lead and an appropriate tool.
   
   IMPORTANT Be careful and don't damage the terminal. Damaging the terminal will require that you replace the connector.

6. 7

   Your multimeter should display 4.5 to 5 Volts on its screen.

CASE 1: The multimeter registered 4.5 to 5 Volts. So far so good since this tells you that the throttle position sensor (TPS) is getting power from the powertrain control module (PCM).

The next step (and the last test) is to check that the BLK/LT BLU wire (which connects to terminal number 1 of the TP sensor's harness connector) is providing Ground. For this test, go to: TEST 3: Verifying TPS Has Ground.

CASE 2: Multimeter DID NOT register 4.5 to 5 Volts. Double check all of your connections and repeat the test.

If your multimeter still doesn't register the 4.5 to 5 Volts DC, then you've just eliminated the TP sensor itself, on your Jeep, as bad. The two most likely reasons for this are: 1) an open in the wire between the TP sensor's harness connector and the PCM's harness connector or 2) the PCM may be fried (although a bad PCM is very rare).

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

TEST 3: Verifying TPS Has Ground

So far, if you've reached this point you have confirmed that the sensor:

One: Is not creating an appropriate throttle position signal (TEST 1).

Two: That the sensor is getting power in the form of 5 Volts from the VIO/WHT wire (TEST 2).

As mentioned earlier, the throttle position sensor (TPS) needs power and Ground to create a throttle angle voltage signal the PCM can use to find out how much you're stepping on or off the accelerator pedal. In this last test step, we're gonna' check that the BLK/LT BLU wire is providing Ground to the TP sensor.

OK, here are the test steps:

1. 1

   Place your multimeter's dial in Volts DC mode.

2. 2

   Disconnect the throtle position sensor from its connector.

3. 4

   Turn the key to the ON position but don't crank or start the engine.

4. 5

   Connect the red multimeter test lead to the positive (+) battery terminal.

5. 6

   Gently probe the terminal labled with the number 1 with the black multimeter test lead and an appropriate tool.
   
   IMPORTANT Be careful and don't damage the terminal. Damaging the terminal will require that you replace the connector.

6. 7

   Your multimeter should display 4.5 to 5 Volts on its screen.

CASE 1: The multimeter showed 11 to 12 Volts. This confirms that the PCM and the wire/circuit (that supply this Ground) are OK.

All three test have confirmed that:

1. The TPS is not providing a varying voltage signal when manually opening the throttle plate.
2. The TPS is being fed 5 Volts DC.
3. The TPS is being fed Ground.

Therefore, you can conclude that the TP Sensor is bad and needs to be replaced (and that this will solve the TP sensor code lighting up the check engine light).

CASE 2: Multimeter DID NOT show 11 to 12 Volts. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.

If your multimeter still doesn't show the indicated voltage, then this indicates a problem with either your Jeep's PCM (internal fault/problem) or an open in the wire between the TPS harness connector and the PCM's harness connector

Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Jeep as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL). You can use the wiring diagram found in the following article to check continuity of the TP sensor circuits:

• 1993-1995 TP Sensor Wiring Diagram (Jeep Grand Cherokee 4.0L).

More Jeep 4.0L Test Tutorials

If this tutorial was helpful/informative, you can find a complete list of tutorials here: Jeep 4.0L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test Trouble Code P0135 (1996-2000 Jeep 4.0L).
• How To Test The MAP Sensor (1997-2003 Jeep 4.0L).
• How To Do A Cylinder Balance Test (Jeep 4.0L).
• Jeep PWM Fan Relay Test Troubleshooting An Overheating Condition.
• How To Test The Crankshaft Position Sensor (1994-1996 4.0L Jeep).