Testing the throttle position sensor on the 1993-1996 5.2L Jeep Grand Cherokee can easily be done with a multimeter.
Although a scan tool is a handy tool to own, you don't need one to test the throttle position sensor.
Testing the TPS involves with three simple test. These three tests are done with a multimeter.
In this tutorial, you'll find all 3 tests explained in detail. With your test results you'll be able to find out if the TPS is bad or not.
Contents of this tutorial at a glance:
APPLIES TO: This tutorial applies to the following vehicles since they use the exact same throttle position sensor: 1993, 1994, 1995, 1996 5.2L V8 Jeep Grand Cherokee.
Symptoms Of A Bad Throttle Position Sensor
As you're probably already aware, the TPS is tasked with informing the fuel injection computer how much the throttle plate opens and closes as you step on or step off the accelerator pedal.
The fuel injection computer then uses this information to be able to inject more or less fuel into the engine (among several things).
Since the TPS is such a critical component of the fuel injection system/engine management system of your 5.2L Jeep Grand Cherokee, when it fails engine performance is going to suffer.
On the 1993-1995 OBD I equipped Jeep Grand Cherokee you'll see following trouble code:
- OBD I Code 24 TPS Voltage Too Low Or Too High.
On the 1996 OBD II equipped Jeep Grand Cherokee you'll see one of the following trouble codes:
- P0121: TPS Voltage Does Not Agree with MAP.
- P0122: Throttle Position Sensor Voltage Low.
- P0123: Throttle Position Sensor Voltage High.
You're also going to see one or more of the following symptoms:
- Won't pass the state mandated emissions test.
- Bad gas mileage.
- Lack of power, rough idle, or hesitation.
- Engine cranks a long time before starting.
Throttle Position Sensor (TPS) Circuit Descriptions
The TPS is a 3 wire type sensor. This means that it has a power wire, a Ground wire and a signal wire. All three wires connect directly the fuel injection computer of your 5.2L V8 Jeep Grand Cherokee.
Since we're gonna' be testing all three wires, the table below has a brief description of each:
| 1993-1995 5.2L Grand Cherokee | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | BLK/LT BLU | Ground |
| 2 | ORG/LT BLU | TPS Signal |
| 3 | VIO/WHT | 5 Volts |
| 1996 5.2L Grand Cherokee | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | BLK/LT BLU | Ground |
| 2 | ORG/LT BLU | TPS Signal |
| 3 | WHT/BLK | 5 Volts |
The throttle position sensor receives 5 Volts and Ground to be able to produce its throttle position voltage signal.
When the throttle places close to, the throttle position sensor produces a voltage signal of about 0.5L to 0.9L Volts DC.
As the throttle plate opens, this voltage signal increases. At wide open throttle, the TPS produces a voltage signal of about 4.5 to 4.7 Volts DC.
As the throttle plate closes, the voltage decreases until it reaches its base voltage (which is usually around 0.5 to 0.9 Volts DC).
When the throttle position sensor fails, its voltage signal usually stays stuck in one value as the throttle plate opens and closes.
Where To Buy The TPS And Save
The throttle position sensor is usually not an expensive engine management component. The following links will help you to comparison shop and hopefully save you a few bucks on the 1990-1991 5.2L V8 Jeep Grand Cherokee's TPS:
NOTE: The above throttle position sensor (TPS) fits the following vehicles: 1990, 1991 5.2L V8 Jeep Grand Cherokee.
TEST 1: Testing The TPS Voltage Signal
Okay, for our first test we're going to check the TPS voltage signal as we open/close the throttle plate.
To check the TPS voltage signal, we need to connect a multimeter to the orange with light blue stripe (ORG/LT BLU) wire of the 3-wire connector.
In the photo above, this water is labeled with the number 2.
As mentioned earlier, the TPS voltage signal should increase/decrease as we open/close the throttle plate.
IMPORTANT: The throttle position sensor (TPS) must remain connected to its electrical connector for this test to function properly. To be able to access the voltage inside the signal wire, you'll need to use either a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.
Let's get started:
- 1
Place your multimeter in Volts DC mode.
- 2
Connect the red test lead to the orange with light blue stripe (ORG/LT BLU) wire of the TP sensor harness connector.
- 3
Ground the black multimeter test lead directly on the battery negative (-) post.
- 4
Manually rotate the throttle.
You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal. - 5
The multimeter should show an increasing voltage as you (or your helper) open up the throttle.
You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal. - 6
The multimeter should show a decreasing voltage as you begin to close the throttle.
- 7
Using a screwdriver's handle, gently tap the TP sensor as you open and close the throttle and observe the multimeter.
The purpose (of tapping the TP sensor with the screwdriver's handle) is to see if the TP sensor shows gaps in the voltage signal. Why? Because a good TP sensor will show a continuous increasing or decreasing voltage signal even while getting tapped by the screw-driver's handle.
Let's analyze your test results:
CASE 1: The TPS voltage signal decreased and increased as you opened and closed the throttle. This is the correct test result and lets you know that the TPS sensor is working correctly (not defective).
You can also conclude that the TPS sensor is getting both power (5 Volts) and Ground from the fuel injection computer.
CASE 2: The TPS voltage signal DID NOT increase/decrease as you opened and closed the throttle. This test result usually indicates that the TPS sensor is defective.
To make sure the TPS sensor is truly defective we have to make sure that it's getting 5 Volts on the violet with white stripe (VIO/WHT) wire. For this test go to: TEST 2: Making Sure The TPS Has 5 Volts.
CASE 3: The multimeter DID NOT register any voltage. This test result usually indicates that the TPS sensor is defective.
To make sure the TPS sensor is truly defective we have to make sure that it's getting 5 Volts on the violet with white stripe (VIO/WHT) wire. For this test go to: TEST 2: Making Sure The TPS Has 5 Volts.
CASE 4: Tapping the TP sensor (with the screwdriver handle) caused gaps in the voltage reading. This test result tells you that the TPS sensor is defective.
Tapping the throttle position sensor with the screwdriver handle should not have any effect on the TPS voltage signal. Since it did, you can conclude that the TPS is defective.
