TPMS Theory & Operation: Sensor Signals And Triggers

TPMS Theory & Operation: Sensor Signals And Triggers

A typical wheel-mounted TPMS sensor will transmit data about tire pressure and temperature. Newer, tire-mounted models can also gauge acceleration and, in some cases, the direction that the wheel is spinning. Some systems display tire pressure by location on the instrument panel, but most do not.

What information is contained in a TPMS signal?

A typical wheel-mounted TPMS sensor will transmit data about tire pressure and temperature. Newer, tire-mounted models can also gauge acceleration and, in some cases, the direction that the wheel is spinning. Some systems display tire pressure by location on the instrument panel, but most do not. Some systems will also transmit battery life information.

How often is a sensor transmitting information?

This varies among manufacturers, but generally, sensors have different settings while parked and while in motion. In rolling mode, sensors transmit, on average, once every 30-120 seconds. While parked or in stationary mode, depending on the manufacturer, sensors may transmit periodically or when a pressure change is detected. If there is a slow leak, it will be ready to display on the dash when the car is started. In the event of rapid air loss, most sensors go into an alert mode that increases the number of transmissions to deliver a swifter warning.

Are TPMS sensors able to report on the status of their battery life?

This depends on the TPMS sensor. There are some models that can send a signal to indicate reduced battery voltage if it goes beyond a specified limit, but not all sensors send such a signal. For instance, cold temperatures can cause a temporary voltage reduction that only corrects itself once the tires warm up. The only proven way to know how much battery life remains is to fully use the sensor to depletion.

But a report on a sensor’s battery life might not be necessary anyway because these batteries have shown to have a fairly long shelf life. Road hazards and environmental decay are much bigger factors in sensor life than battery depletion, which underscores the need for proper service of TPMS sensors. Be sure to replace the wear items – the valve core, assembling nut, seal and dust cap – when necessary.

What signals from inside the shop can interfere with TPMS signals?

Direct TPMS uses radio signal technology and is prone to interference. The majority of TPMS sensors are activated with a low frequency (LF) signal (125 KHz). This LF signal varies from vehicle to vehicle (some require more power than others) and forces the sensor to transmit. The TPMS sensors then transmit information and communicate via a UHF signal (314.9-433.92 MHz). Anything transmitting in this range, or anything that would block a radio signal. But interference isn’t too common, overall, and requires the interference source to be within close range and remain constant for a period.

Just be aware that if there is interference, especially inside the shop, moving the vehicle outside (or even sometimes another foot or two if the caliper is causing the interference) is usually enough to clear things up.

You May Also Like

The Winter Tire Opportunity – Now Is The Time

Winters tires aren’t just a luxury, it’s your job to tell your customers the positive impact that the tires can give them.

It was a frigid February morning in Chicago last year. The kind of cold that creeps into the depths of your lungs, making it difficult and even a little painful to breathe. The kind of cold that literally takes your breath away. The snow was falling as I stepped into my car and took off across The Chicago Skyway with the city lights in my rear view. It was around Gary, Indiana, that the lake effect snow engulfed Interstate 90 and made it impossible to see the road more than about 15 feet ahead as I made an unwise attempt to pass a massive snowplow in the right lane. And, it was this moment that I understood the difference between an all-season tire and a true winter tire. My life as a “tire guy” would never be the same again.

Diagnosing Audi A8 TPMS Issues

These are all the steps you’ll need to pinpoint fault issues in TPMS for 2009-2016 Audi A8 vehicles.

The Rule of 3X Tire Rotation

Proper rotation procedures maximize tread life and customers coming back.

Communicating The Effectiveness Of TPMS

A good angle to start with may be laying out the consequences of not having a working TPMS.

Servicing Tires With 18-In.-Plus Rims

Servicing any tire and wheel assembly correctly starts with having the right equipment.

Other Posts

ATEQ TPMS Tools Adds Tesla BLE Function To VT67

ATEQ’s new VT67 TPMS Tablet will be capable of reading and programming the Tesla BLE sensor.

TPMS Valve Stems – What Are The Trends? What Is The Future?

Whatever the type of stem, carelessness can result in a broken sensor or even a customer being stranded with a flat tire.

Nissan TPMS Service

The behavior of the TPMS systems is very consistent across all Nissan models.

TPMS Sensor Signals

TPMS sensor signals are low power and low frequency, with most sensors transmitting at 315MHz or 433MHz.