Every vehicle comprises tens of thousands of parts that work in tandem at all times to enable you to drive. Most times, a malfunction in a small part can cause entire systems to fail. The throttle position sensor is one such part, so what happens if you disconnect it?
Disconnecting the throttle position sensor leaves your engine control unit (ECU) confused about the position of the throttle, which has various consequences depending on the type of car you drive. The ECU might turn the engine off or reduce the car’s power.
This article looks at whether you can bypass the throttle position sensor and what happens if you disconnect it. I also explore the possibility of a car running without a throttle position sensor and whether disconnecting the battery will reset the sensor.
Can You Bypass the Throttle Position Sensor?
The throttle position sensor keeps track of your car’s throttle and reports to the engine control unit or engine control module (ECM). It gives feedback on your acceleration and deceleration to the ECU and helps it determine how much fuel it should deliver to your engine.
While it may be possible for you to bypass the throttle position sensor (TPS), it is not something you should do. The dangers that come with driving without a well-functioning TPS are too great to risk.
You can probably bypass it temporarily by following these steps:
- Disconnect the TPS.
- Turn on the ignition.
- Wait for 30 seconds.
- Restart the engine.
- Your car should start without a hitch.
After doing these, it may take a while for the ECU to realize that the TPS is not working and readjust its operations.
What Happens If You Disconnect the Throttle Position Sensor?
With driving cars, some things are certain. For example, when you step on the gas pedal, your vehicle will undoubtedly speed up—until it doesn’t, because of some issues.
Amongst the many issues that cause your car to run roughly or prevent acceleration, the throttle position sensor is a common culprit. The TPS plays a significant role in your engine’s fuel economy. If it is not functioning because of a fault or disconnection, your car will have problems with acceleration and running.
What happens if you disconnect your throttle position sensor depends on the car you drive. Generally, a light on the dashboard comes on, and your car might not run at all. Some cars enter a “limp home” mode or “limp mode,” like when the TPS fails.
In this mode, the ECU greatly reduces your engine’s power, leaving just enough juice to get your car home or to a repair shop so someone can give it a proper check. You will see a dashboard light displaying an engine icon with a lightning bolt in it, or a half-filled icon.
Some cars may be hard to start if you unplug the TPS when it’s not running, while others may carry on if you disconnect it while it is running. Things may remain normal when you are idling, but the ECU gets confused about what to do once you accelerate.
The ECU may substitute a random value for the TPS reading and allow you to drive the car with a TPS and CEL code.
Can a Car Run Without a Throttle Position Sensor?
A car can run without a TPS, but it will run poorly, and it will work like a car with a bad or failing TPS. These indicators of a failing TPS include:
- A decrease in fuel efficiency
Your engine becomes inefficient and wastes fuel without the precision monitoring the throttle position sensor provides.
- Your car might accelerate, but it won’t go past a specific speed level.
- Lack of power
If the TPS is absent or malfunctioning, putting your foot on the gas pedal might result in no speed or too much speed. You may find your vehicle speeding when you don’t intend to do so.
- Your car cannot maintain a constant engine speed when idling because a constant level of fuel delivery is necessary for this to happen.
While a car can run without a TPS, driving without puts you and other motorists at risk.
Will Disconnecting the Battery Reset Throttle Position Sensor?
Resetting or reprogramming your throttle position sensor might solve some problems with the sensor. It is also necessary to recalibrate the settings when you install a new sensor to drive smoothly.
For most cars, disconnecting the battery or removing the fuse for the ECM is the easiest way to reset the throttle position sensor. Sometimes, resetting the ECM does not affect the TPS.
When you go the battery route, disconnect the negative cable from the battery and wait for up to 5 minutes before reconnecting it. If you aren’t comfortable with the workings of electricity, do not attempt to do this yourself. Fiddling with the wrong fuse or cable could be dangerous for you.
Some vehicles like Toyota have other means of resetting the TPS apart from disconnecting the battery. They include:
1. The first throttle sequence
- First, warm up your engine to the optimal running temperature by driving (if safe) or idling the car while adding some gas.
- Put the key in the ignition and turn it to the On position without cranking the engine.
- Turn it off after waiting for a few seconds.
- Repeat step two and crank the engine.
- Pull the parking brake.
- Set the gear lever in Drive and wait for five to 10 minutes.
This method works best when you need a jumpstart or have a dead battery.
2. The second throttle sequence
- Put the key in the ignition and turn it to the On position without cranking the engine.
- Slowly press on the gas pedal, hold it for three seconds, and release it slowly.
- Repeat this three times, then put the key in the Off position and remove it.
- Wait for five to 10 minutes.
- Second Throttle Sequence
It works on Toyota Tacoma, produced between 2005 and 2015, and other models. You also don’t need to warm up the engine.
If the problems with your TPS persist, you should take your car to a professional mechanic for a proper diagnosis and repair.
