In this tutorial, I'll walk you through the steps to test the throttle position sensor (TPS) on a 1997–2001 2.2L Toyota Camry.
The great thing about this test is that you can do it quickly and accurately using just a multimeter. That's right—there's no need for any pricey diagnostic tools to check if the TPS is working properly.
I'll break down the process into three simple tests. By the end, you'll have all the information you need to determine if the TPS is faulty.
Contents of this tutorial:
NOTE: This tutorial applies to the following vehicles:
- 2.2L Toyota Camry: 1997, 1998, 1999, 2000, 2001.
Symptoms Of A Bad Throttle Position Sensor
The throttle position sensor (TPS) measures the angle of the throttle plate inside the throttle body.
As you may already know, the throttle plate is connected to the accelerator pedal via an accelerator cable.
When you press the accelerator pedal, the throttle plate opens, allowing more air to flow into the engine. When you release the pedal, the throttle plate closes, reducing the air entering the engine.
The fuel injection computer relies on the TPS to monitor how much the throttle plate opens or closes, making it a crucial part of the fuel injection system.
When the TPS fails, it can significantly affect the performance of your 2.2L Toyota Camry's engine. You're likely to notice one or more of these symptoms:
- The check engine light (CEL) is illuminated on the instrument panel.
- A TPS diagnostic trouble code (DTC) is stored in the PCM's memory:
- P0120: Throttle Position Sensor Circuit Malfunction.
- P0121: Throttle Position Sensor Circuit Range/Performance Problem.
- Poor gas mileage.
- Hard starts or extended cranking time after shutting the engine off.
- Black smoke coming from the tailpipe.
- Hesitation when accelerating.
Circuit Descriptions Of The TPS
| Camry TPS Pinout | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | Light Green (LT GRN) | TPS Signal |
| 2 | Brown (BRN) | Sensor Ground |
| 3 | Yellow (YEL) | 5 Volts |
To accurately diagnose the throttle position sensor (TPS), it's essential to understand how it works. The TPS generates a voltage signal that changes as the throttle plate moves. This signal allows the fuel injection computer to monitor the throttle plate's position.
- When the throttle plate is fully closed, the TPS typically produces a voltage signal between 0.5 and 0.9 volts DC.
- As the throttle plate opens —like when you step on the accelerator pedal— the voltage signal steadily increases. At full throttle, this signal can reach around 4.5 to 5 volts DC, depending on the vehicle.
If the throttle position sensor fails, one of the most common issues is that the voltage signal gets "stuck" at a single value, regardless of the throttle plate's position.
This means the TPS isn't accurately reporting the movement of the throttle plate to the computer, leading to performance problems.
Where To Buy Your TP Sensor And Save
Where can you buy the TP sensor for your 2.2L Toyota Camry? You can buy it at your local auto parts store but it's gonna' cost a whole lot more. I suggest taking a look at the price of the TP sensor in the following links and compare:
Not sure if the above TP sensor fits your particular 2.2L Toyota Camry? Don't worry, once you get to the site, they'll make sure it fits by asking you the particulars of your vehicle. If it doesn't fit, they'll find you the right one.
TEST 1: Testing The Throttle Position Sensor Voltage Signal
To determine if the throttle position sensor (TPS) is faulty, we'll connect a multimeter to the light green (LT GRN) wire on the TPS's 3-wire connector.
Next, we'll manually open and close the throttle plate while monitoring the voltage signal on the multimeter.
- If the TPS is working correctly, the voltage signal will increase smoothly as you open the throttle plate and decrease as you close it.
- If the TPS is defective, the voltage signal will stay stuck at one value, regardless of the throttle plate's position.
IMPORTANT: For this test to work, the throttle position sensor must stay connected to its 3-wire connector. You'll need to use a back probe or a wire-piercing probe to access the TPS signal. You can see an example of this tool here (and where to buy it): Wire Piercing Probe.
Let's get started:
- 1
Place your multimeter in Volts DC mode.
- 2
Connect the red test lead to the LT GRN wire of the TP sensor's connector.
- 3
Ground the black multimeter lead directly on the battery negative (-) post.
- 4
Manually open the throttle plate.
You'll get the best results by opening and closing the throttle plate 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 plate 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 plate.
- 7
Using a screwdriver's handle, gently tap the TP sensor as you open and close the throttle plate 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 examine your test results:
CASE 1: The voltage increased/decreased as you manually opened/closed the throttle plate. This test result confirms that the TP sensor is OK and not defective.
CASE 2: The voltage DID NOT increase/decrease as you manually opened/closed the throttle plate. This tells you that the throttle position sensor (TPS), on your Camry, has a problem.
Before condemning the TPS as bad, you need to make sure that it's getting both 5 Volts and Ground. For the next test, go to: TEST 2: Making Sure The TPS Has 5 Volts.
CASE 3: The multimeter DID NOT register any voltage. This test result doesn't condemn the TP sensor as bad just yet.
Why? Because the TP sensor may be missing either 5 Volts or Ground. So the next step is to check that the TP sensor is getting 5 Volts, go to: TEST 2: Making Sure The TPS Has 5 Volts.