When your Celica is having a hard time starting, or won’t idle properly a common cause is a failing Celica TPS Sensor. The TPS is also known as the throttle position sensor, and it’s mounted to the throttle body shaft of your 2.2 liter engine. As your Celica engine is running and you push down on your gas pedal, the throttle body opens. The angle of your throttle body blade is measured by your throttle sensor, and transmitted to your Toyota engine computer.
The Celica TPS sensor is a simple potentiometer, and it transmits the angle of your throttle through a four pin engine harness. These pins are power, ground, idle switch and the signal which I will show you how to test in this DIY tutorial. When this throttle position sensor starts to fail, you will see a variety of common Toyota Celica issues.
Today I’ll be showing you how to test the Celica TPS in a 1998 Toyota with the 2.2 liter 5SFE engine in it. In order to complete this guide however, you’re going to need a voltmeter or similar device like a digital multimeter.
Common Celica TPS Sensor Symptoms
Some of the more common throttle position related symptoms range from severe to your engine not starting. If you are wondering whether or not your throttle position sensor has failed, here’s a few of the common Celica issues you might encounter.
- Poor engine idle
- Inconsistent throttle response
- Engine pinging or detonation
- Bad gas mileage
- Celica won’t idle
- Check Engine Light ON
When you have the Toyota Celica check engine light on, you’ll need an OBDII scan tool to check your car. If the throttle position sensor has gone bad in your Celica, there’s a good chance your 2.2L engine will run rich and use too much fuel.
This condition will do more than hurt your pocketbook and waste gas. The excessive hydrocarbons in your combustion chamber can break down your engine oil, and elevate your exhaust gas temperature to dangerous levels. If your exhaust gases get hot enough it will burn out your catalytic converter, making for a very expensive repair.
If your Celica won’t stay on or has trouble maintaining the idle, the TPS sensor is a common issue. This is due to the idle switch that’s located on PIN C of our Celica throttle body wiring diagram shown below. When this switch has failed your Toyota engine computer will have a hard time maintaining idle.
Testing your Celica TPS for Power
The first order of business in this Celica TPS testing guide is to make sure that your throttle sensor has power and ground. To do this you’ll need to open your Celica hood and locate the throttle body.
The throttle sensor is mounted to the opposite side of your throttle cable and butterfly.
Disconnect the four wire TPS connector, and then turn your Celica ignition to the “ON” position.
The wire you will be checking is the RED one that leads to PIN D of your throttle sensor. This wire should be carrying a 5 volt switched power signal to your TPS sensor.
If this checks out the next wire to check is the BROWN wire that leads to PIN A. This wire should provide you with a low reference ground signal. After checking for both power and ground here, you should know that your Celica TPS has the power it needs to properly operate.
Testing your Celica TPS Signal
Now that you’ve ensured your throttle sensor is getting power and ground, you need to check the signal wire. Plug your Celica TPS back in and you can use either a multimeter to pierce the signal wire, or your scan tool to read the Live Data of your OBDII Diagnostic Computer.
Doesn’t matter whatever method you feel comfortable with, so long as your DTC reads in voltage. You do not need to turn your Celica engine on for this part of the test, just keep the ignition to the “ON” position.
The wire you need to pierce will vary depending on your year range of Toyota. If you own a 1992-1993 Celica the signal wire for your MAF is at PIN C and is a BLACK wire with a PINK stripe in it. If you own a 1994-1999 Toyota the mass air flow sensor signal wire is a BLACK wire with a WHITE stripe in it.
If you are using a multimeter to measure the signal, you can manually open and close the throttle body. Using a scan tool? No problem just sit in your Celica and push down on the gas pedal to open and close the throttle blade.
With the throttle body in the closed position, resting against the stop screw the voltage at this signal wire should read between .2 and .9 Volts DC. Now push open your throttle or push down on the gas pedal and this voltage should increase to between 3.5 to 4.5 Volts DC.
Close the throttle slowly and monitor the voltage, it should sweep down smoothly and scale upwards in the same manner. It should not peak or spike, and there should not be any missing voltage gaps.
If your Celica TPS sensor does not respond in this manner, it’s time to remove it and install a replacement Toyota throttle sensor. You will need to use your digital multimeter to calibrate the new TPS sensor. Use your OBDII scan tool to clear your Celica check engine light, and get your Toyota back on the road.
Have any questions about our How To guide? Leave us a comment below and let us know!
