How To Test The TPS w/ Manual Transaxle (1987-1991 2.0L Toyota Camry)

The throttle position sensor (TPS) on the 1987-1991 2.0L Toyota Camry with a manual transmission is just a 3-wire TPS sensor.

In this tutorial, I'll explain how to test the throttle position sensor with a multimeter to find out if it's good or bad. All of the test steps are explained in a step by step manner.

APPLIES TO: This tutorial applies to the following vehicles:

• 2.0L Toyota Camry: 1997, 1988, 1989, 1990, 1991

Symptoms Of A Bad Throttle Position Sensor

The throttle position sensor (TPS) provides the fuel injection computer with a voltage signal that reflects the exact position of the throttle plate.

The fuel injection computer uses this information is essential for tasks like fine-tuning fuel delivery and adjusting ignition timing.

When the TPS isn't functioning correctly, it can lead to several problems, including:

• OBD I Trouble Code: Diagnostic trouble code 41 may appear, indicating an issue with the TPS signal.
• Hesitation: The engine may hesitate or stumble during acceleration.
• Power Loss: A defective TPS can cause a noticeable drop in engine performance.
• Poor Fuel Efficiency: Incorrect fuel delivery can result in reduced gas mileage.

How The TPS Works

On the 1987-1991 2.0L Toyota Camry with a manual transaxle, the throttle position sensor (TPS) is a 3-wire sensor (unlike the automatic transaxle model).

Unlike variable resistor-type TPS sensors, this TPS includes two switches:

• IDL (Idle Switch): Signals the ECU when the throttle plate is fully closed (idle position).
• PSW (Power Switch): Activates at approximately two-thirds throttle, signaling the ECU that the throttle is significantly open.

The primary role of this TPS is to detect specific throttle positions and relay that information to the fuel injection computer. The computer then uses this data to adjust:

• Fuel injection timing.
• Ignition timing.
• Other engine parameters for optimal performance under various driving conditions.

Circuit Descriptions Of The TPS

Terminal	Wire	Description
1	Black with red stripe (BLK/RED)	Power Switch (PSW) Signal
2	Brown (BRN)	Chassis Ground
3	Blue (BLU)	Idle Switch (IDL) Signal

Where To Buy The TPS And Save

The following links will help you to comparison shop for a new 2.0L Camry TPS. I think they'll save you a few bucks:

Not sure if the above TPS fits your particular 2.0L Toyota Camry? Don't worry, once you get to the site they'll make sure it fits by asking you the specifics of your particular Toyota vehicle. If it doesn't fit, they'll find you the right one.

TEST 1: Making Sure The TPS Is Getting Power

For our first test, we're gonna make sure that:

• The blue (BLU) wire is delivering 10 to 12 Volts DC.
• The black with red stripe wire (BLK/RED) wire is delivering 4.5 to 5 Volts DC.

If the indicated voltages are present in the BLU and BLK/RED wires, we'll move on to TEST 2 and make sure that the BRN wire is providing Ground.

NOTE: We'll be checking for the presence of these voltages on the TPS 3-wire connector. This connector has female terminals.

Here are the steps:

1. 1

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

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Disconnect the TPS from its 3-wire connector.

4. 4

   Ground the black multimeter test lead on the battery negative (-) terminal.

5. 5

   Probe the female terminal that corresponds to the BLU wire of the TPS 3-wire connector with the red multimeter test lead.
   
   NOTE: This test is done on the TP sensor's 3-wire connector that has female terminals.

6. 6

   Your multimeter should report a voltage between 10 to 12 Volts DC.

7. 7

   Probe the female terminal that corresponds to the BLK/RED wire of the TPS 3-wire connector with the red multimeter test lead.
   
   NOTE: This test is done on the TP sensor's 3-wire connector that has female terminals.

8. 8

   Your multimeter should report a voltage between 4.5 to 5 Volts DC.

Let's take a look at your test results:

CASE 1: The indicated voltage values were present. This is the correct and expected test result.

Your next step is to go to: TEST 2: Making Sure The TPS Is Getting Ground.

CASE 2 The indicated voltage values WERE NOT present. This test result usually indicates one of the following issues:

• There's an open-circuit issue in the wire between the TPS connector and the fuel injection computer.
• The fuel injection computer isn't getting power on pin 1 of the computer's 14-wire connector.
• The fuel injection computer is bad (very rare).

Although beyond the scope of this tutorial, your next step is to find out why power is missing in the terminal you just tested.