Most modern cars arrive with a tire pressure monitoring system (TPMS), which, from its name, should have been self-explanatory enough. Yet, to my surprise, novices are still oblivious to their design intention and have no clues why it is included in the package.
Hence, I wrote this brief guide to explain and debunk all myths surrounding that system. All will be revealed in the sections below.
In this article:
What Is A Tire Pressure Monitoring System (TPMS)?
TPMS is designed to warn drivers of wrongly-inflated tires that might result in unsafe driving. It goes with a yellow indicator, which lights up on the car’s instrument dashboard whenever the air pressure goes bad. From your driver’s seat, you can see a tire pressure icon (resembling horseshoes) with big exclamation points.
Although there are no two identical TPMS setups, they can generally be divided into two types of tire pressure system: Direct and Indirect TPMS.
How Do Tire Pressure Sensors Work?
1. Direct TPMS
- Actual tire pressure readings (more accurate than Indirect TPMS)
- No need for resetting after tire inflation/tire rotation
A direct TPMS utilizes pressure sensors inside each tire to track its specific tire pressure level. It does not merely rely on the antilock braking system or rate of revolution.
How does it go?
- First, the entire sensors are activated to yield accurate tire pressure readings and detect ambient temperature variations.
- The sensors then send all this data to a CCM (centralized control module) to be interpreted, analyzed, and transmitted to the dashboard. If troubles ensue, they trigger the indicator light to flash and send off warning alerts.
This entire transmission process is wireless for my Jeep, though other car models might be designed differently. Also, since each direct sensor pairs with a different serial number, the TPMS can easily distinguish varied readings among individual tires and also differentiate itself from other vehicle systems.
Even an old car (like my Jeep) might use pretty high-end technology for TPMS. Hence, never dare replace broken TPMS on your own; to make it compatible and consistent with the rest of the car, always turn to a knowledgeable, experienced technician.
2. Indirect TPMS
- Measuring tire pressure from wheel revolution rate
- Might show inaccurate readings for new, different tire sizes
- The tire pressure indicators require reset after tire inflation and/or rotation
- Cheaper than its direct counterpart
Indirect tire pressure monitoring system relies on the wheel speed sensor system used on anti-locking brakes. More specifically, the sensors measure each wheel’s revolution rate and translate it onto onboard computers, then compare the results to other vehicle data (ex: maximum speed rating).
Your car computer will roughly calculate the tire’s relative size from the wheel’s revolution rate. Whenever the wheel spins faster than required, the sensors detect underinflation issues and alert you accordingly.
As you can see, indirect TPMS does not really measure the actual tire pressure. Its electronic process never involves the same measurements observed on a typical tire gauge or direct TPMS.
The entire concept is just to assess how fast the tires rotate and send corresponding signals once the rotation becomes problematic. Hence, inaccurate or amiss readings are inevitable.
1. Low Air Pressure
Of course, the dashboard indicator light is designed to flash when the TPMS detects insufficient PSI.
- Addressing The Issue:
Check the car’s recommended PSI (pounder per square inch) and inflate your tires to proper tire pressure accordingly. The process is often straightforward and quick – since the likelihood of all four tires encountering pressure issues is quite low.
Once done, get in your car to drive it for a few short rounds, checking whether the TPMS light jumps out again.
2. Issues With The Pressure Monitoring Sensors
Does the TPMS flash in 60-90 seconds and then stay illuminated? Then, your tires do not have any problems that need addressing. It’s the sensors themselves that malfunction.
- Addressing The Issues:
Check and replace/repair any broken TPMS components as fast as possible. Trust me; putting it off is a bad idea! According to the NHTSA, tire-related accidents have taken 664 lives in 2020.
3. Tires Wrongly Installed
Improperly-installed tires result in incorrectly-positioned TPMS sensors and, in turn, cause the flashing lights.
- Addressing The Issue:
Check all your tires at least once per week to ensure their sensors are firmly secured and working correctly.
4. The TPMS Fails to Be Initialized
This issue often happens when you install new tires, and the TPMS gets confused by the unfamiliar data.
- Addressing The Issue:
Read your car manual to initialize the TPMS as the instructions describe. The method works most of the time – and when it doesn’t, take my commercial vehicle to professionals for help.
Is It Safe to Drive With The TPMS Light On?
Yes, if the light is on due to faulty sensors/bad units rather than under-inflated tires.
Still, there’s no way to be certain unless you get out of the car to check. Anytime the lights flash, I always stop my Jeep to get to the bottom of the problem before continuing to drive.
Is It Alright to Drive With No TPMS Installed?
Yes – though it’s very inconvenient, since you now have to perform manual checks much more frequently to avoid inflation issues and premature tire wear.
Bring a gauge with you to check the air pressure every few hundred miles. If you have no gauges or other diagnostic tools, ask for one at a gas station or tire shop; the auto repair facility usually lets me borrow it for free.
I hope my answer has satisfied you. Learning how the TPMS functions is important; otherwise, you will always have to brace yourself for tire blowout, tire failure, or even accidents!
Good luck with your driving, and send me letters if certain TPMS aspects still sound baffling.
See more: How to reset tire pressure sensor?