The Corvette Powertrain Control Module determines the angle of your LS1 throttle through the use of your Corvette TPS Sensor. This sensor is mounted to the shaft of your GEN III throttle body. When you push down on your accelerator pedal in your ‘Vette, the throttle cable opens the throttle body. This allows more air to enter your LS1 engine and your engine speed to increase.
The way this unit works is exactly the same as many other GEN III engines. The Corvette TPS Sensor is a three pin unit that uses a power, ground and signal to operate. This sensor is a basic potentiometer, meaning it’s designed to measure the angle of your throttle blade.
Today I’ll be showing you how to test your Corvette TPS Sensor in a 2000 Chevy with the robust 5.7 liter LS1 in it. This test requires the use of a digital multimeter, so if you aren’t sure what that is check this guide here. You do not need to turn on your engine to test this sensor, and it’s very easy to do.
If the Corvette TPS Sensor in your Chevy is going bad, you’ll see several issues right away. One of the most obvious Chevy Corvette problems is the check engine light turning on in your dash. This light can also be shaped as a yellow wrench next to your IPC or display center.
If your C5 check engine light is on, you’ll need to use the right OBDII scan tool to pull the codes. When the alphanumeric OBDII code tells you that your throttle sensor is going bad, you’ll need this DIY guide to test it.
Chevy Symptoms of a bad Corvette TPS Sensor
Outside of the check engine light being on in your C5 instrument cluster, there’s quite a few other Chevy Corvette issues you’ll notice. Here’s just a few below.
- Inconsistent throttle response
- Engine revs on it’s own
- Engine stalls
- Throttle won’t respond
- BAD gas mileage
- Engine Light ON
Once you have determined that your throttle sensor is the culprit, you will begin by testing the TPS for power.
Testing your Corvette TPS Sensor for Power
In order to test for power, you’ll need to insert your C5 key and turn the ignition to the “ON” position. This sends power from your LS1 ECU to your engine sensors. This test can also be done in any LS1 swapped vehicle, regardless of what vehicle you own.
Open your Corvette hood and locate your throttle position sensor. Reach around and pull up on the TPS connector tab to disconnect it. Now that you’ve got the Corvette TPS sensor connector free you can test for power at the wiring harness.
The pin on the wiring harness you are checking first is PIN C. Refer to the Corvette TPS sensor wiring diagram to the left to locate this wire. Remember you are testing the ENGINE harness side, not the throttle sensor itself.
When testing this pin make sure to never force the metal lead of your multimeter into the harness. This can cause damage to the pin and create issues with connectivity, which is not what you want to do to any LS1 sensor.
If your TPS is receiving power, you’ll have around 5 volts of DC power here at this wire. If that’s good the next wire to check is the ground signal which is PIN B. There should be a ground signal here at this wire. If you have both power and ground great, your TPS sensor is checking out so far.
Depending on your OBDII check engine code, you may have other issues with your throttle body. If the trouble code you have is a P0122 or a P0123, this is a sign that your Corvette TPS Sensor isn’t sending the right voltage. When the voltage signal from your LS1 throttle body is too high or too low, you’ll have the Throttle Position Circuit Low or High Input.
At this stage you should know that your TPS is getting power and ground. So the next step is to check the signal at your throttle sensor.
Measuring your LS1 throttle sensor signal
You will need to plug your Corvette TPS sensor back in place before you proceed with this test. Once it’s plugged back in the wire you need to test is the one that leads to PIN A. You can do this by putting the black lead of your multimeter on the battery negative terminal, and then piercing the wire with the red lead.
Don’t forget that your ignition key should be at the “ON” position. With your LS1 throttle completely at the closed position, you should read a signal voltage range between .5 to .9 Volts. This represents your base TPS voltage in your Chevy Corvette.
Now manually deflect your LS1 throttle so that it’s fully opened. Measure the Corvette TPS sensor signal with the throttle opened fully. This is also known as Wide Open Throttle. If you haven’t already, check our guide on modifying your LS1 throttle body for fully open operation.
When your throttle is fully open at the Wide Open Throttle position your signal should read between 4.5 to 4.9 Volts of DC power. If it doesn’t or the voltage does not read, it’s a clear sign that your Corvette TPS Sensor is dead.
Use this guide to install your LS1 throttle sensor, and follow our guide to calibrate your replacement C5 throttle Sensor. Want more information on your LS1 or how to plan your LS1 swap? Check our guide below.
How To Plan Your LS1 Swap
Love it or hate it, the LS1 engine swap has definitely taken on a life of it's own in recent years. Tuners and engine swappers who are used to importing engines from overseas to swap into their cars, have now turned to the GEN III GM engine known as the LS1. What is the LS1? Technically, it's the engine code or GM RPO for the very popular 5.7 liter small block first found in the 1998-2001 Camaro, Firebird, and TransAm.
It's also found in the Corvette, making the GEN III LS1 engine one of the most robust and flexible small block V8 engines in history. For the purposes of this list however, the term LS1 encompasses the entire range of GEN III engines, which includes many popular budget LS engines that can be swapped into your chassis.
So this list of how to plan your LS1 swap will help you identify,and plan for your engine swap, no matter what donor car you are putting it into. We'll try to cover all the points on this list, and as always if you have any corrections or ideas on how this list can improve, let us know!
Pick and Prepare your Donor Chassis
Picking your chassis and preparing it is a step you should take care of now so that you know what you'll need to complete the LS1 swap. Removing your factory engine isn't as hard as you might think.
Once you have the engine removed, you can move onto the next step in how to plan your LS1 swap.
Have any questions about our DIY guide to testing a Corvette TPS Sensor? Leave us a comment below and let us know!