tire PRESSURE MONITORING SYSTEM (TPMS)

Here you will find useful information and important tips relating to tire pressure monitoring systems in vehicles.

tire pressure monitoring system (TPMS)

From the end of 2014, all new vehicles have a tire pressure monitoring system on board as standard. It provides a warning about insufficient tire pressure and protects the driver against increased fuel consumption and tire damage. On this page, those interested in technology will find a whole host of details relating to the respective system variants, practical tips for changing tires, and important information to be taken into account during tire fitting.

Important safety information
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.

 

tire PRESSURE MONITORING SYSTEM: Basics

tire pressure is an essential safety factor of a vehicle. The most common tire damage can be traced back to a gradual pressure loss. This is often noticed by the driver of the vehicle when it is too late. Insufficient tire pressure causes increased fuel consumption and poor driving characteristics. Increased tire temperature and greater wear are also linked to this. Insufficient tire pressure may cause the tire to suddenly burst. This is an extremely high safety risk for all those in the vehicle. This is why tire pressure monitoring systems (TPMS) have been mandatory since November 2014 for all new vehicles in the EU.

 

The general parts aftermarket also offers different systems for retrofitting. tire pressure monitoring systems monitor the tire pressure and tire temperature. tire pressure monitoring systems have been on the market for a while, mostly in top-end vehicles. In the USA, they have been mandatory for new vehicles for several years. It is therefore time for all workshop staff to familiarise themselves with this topic. because even during a wheel change, a lack of knowledge about the systems can lead to impairment of the tire pressure monitoring system.

 

We differentiate between two fundamentally different systems: Indirect and direct tire pressure monitoring systems.

INDIRECT tire PRESSURE MONITORING SYSTEM: FUNCTION

In indirect measuring systems, the pressure is monitored using ABS sensors on the vehicle. The ABS control unit detects the pressure loss of a tire through the different rolling circumference. A tire with a low air pressure makes more revolutions than one with the correct air pressure. However, these systems are not as precise as direct measurement systems, and require a pressure loss of approx. 30% before there is a warning message.

 

The advantage is the relatively low price as numerous vehicle components already in place can be used. The only things required are adapted ABS software and an additional display in the instrument unit.

DIRECT tire PRESSURE MONITORING SYSTEM: FUNCTION

Direct measurement systems are considerably more precise, but also involve more outlay, and are therefore more expensive. Here, a battery-powered sensor is located in each wheel. This measures the temperature and the pressure of the tire, and transfers the measured values wirelessly to the tire pressure monitoring system control unit and/or the display unit. One or more antennas transmit the radio signal.

 

Direct systems compare the tire pressure with a reference value stored in the tire pressure monitoring system control unit. This has the advantage that pressure losses of several tires can be detected at the same time. This may mean that, following a tire change, a re-adjustment (calibration) or re-coding of the sensors is required.

 

A further disadvantage of the direct measuring systems is that the batteries have to be replaced after approx. 5 – 10 years. As, depending on the manufacturer, these form a unit with the sensors, this often means complete replacement of the sensor unit.

 

If the batteries have to be replaced, this is shown in a timely manner by the display unit, meaning that a sudden system failure is avoided. When changing from summer to winter tires, it should be ensured that additional wheel sensors are attached, or that existing sensors are modified. Certain important points should be noted so that no damage or functional problems occur during tire fitting.

WHAT SHOULD YOU PAY ATTENTION TO DURING WHEEL AND tire FITTING?: PRACTICAL TIPS

Before changing a wheel or tire, you should always check to what extent the vehicle has a tire pressure monitoring system. This can be ascertained, for example, from a coloured valve, a coloured valve cap, a symbol in the instrument cluster, or an additional display unit (for retrofitted systems). It is recommended that you ask the customer about any tire pressure monitoring systems directly during vehicle handover and point out the special features.

For active systems, the following points must be observed:

  • During removal of the tire, the removal lever must only be applied on the opposite side to the valve on both sides of the tire (Fig. 1).
  • When dismounting the tire, the mounting head must be placed approx. 15 cm behind the valve (Fig. 2).
  • Avoid any force being applied to the sensor.
  • During removal and mounting of the tire, tire bead and rim flange may only be wetted with mounting spray or soap solution. Using mounting paste may cause the filter surface of the sensor electronics to clog.
  • The sensor may only be cleaned with a dry, lint-free cloth. Compressed air, cleaning agents, and solvents must not be used.
  • Before mounting a new tire, the sensor unit must be checked for dirt, damage, and tight fit.
  • Replace the valve insert and/or the valve (depending on the manufacturer's specifications). Observe the tightening torques.
  • Following mounting, carry out calibration/re-coding with cold tires if applicable.
  • Information from the vehicle and system manufacturers should be noted separately.

 

As there are numerous systems on the market which operate differently, the manufacturer-specific installation instructions must also be observed if possible.

tire PRESSURE MONITORING SYSTEMS: OVERVIEW

System Manufacturer Description Used for
TSS Beru tire Safety System – direct measurement
tire pressure monitoring system with four separate antennas
Audi, Bentley, BMW, Ferrari, Land Rover, Maserati, Maybach, Mercedes, Porsche, VW, commercial vehicles
SMSP Schrader, sales in Germany: Tecma Direct measurement tire pressure monitoring system with a central antenna Citroen, Opel, Peugeot, Renault, Chevrolet, Cadillac
DDS Continental Teves Deflection Detection System – indirect measurement tire pressure monitoring system BMW, Mini, Opel
TPMS Continental Teves tire Pressure Monitoring System – direct measurement tire pressure monitoring system Opel/Vauxhall
VDO BMW, Citroen, Fiat, Ford, Honda, Hyundai, Infiniti, Jaguar, Jeep, Kia, Lada, Lancia, Land Rover, Mazda, Mercedes Bens, Mini, Mitsubichi, Nissan, Peugeot, Renault, Suzuki, Tesla, Volkswagen, Volvo
Warn Air Dunlop Indirect measurement tire pressure monitoring system BMW, Mini
tire Guard Siemens VDO Direct measurement tire pressure monitoring system with a sensor which has been permanently integrated into the tires without a battery Renault
Smar tire Sales: Seehase Direct measurement tire pressure monitoring system for retrofitting Universal
X-Pressure Pirelli Direct measurement tire pressure monitoring system for retrofitting Universal
Road Snoop Nokian Direct measurement tire pressure monitoring system for retrofitting Universal
Magic Control Waeco Direct measurement tire pressure monitoring system for retrofitting Universal

No liability assumed

tire SAFETY SYSTEM (TSS) BERU: WORKSHOP TIPS

The TSS from Beru is installed in series by many vehicle manufacturers, but is also offered as an accessory for retrofitting. BMW calls the Beru system "RDC" (Reifen Druck Control, or tire Pressure Control); at Mercedes and Audi it is the "tire pressure control system". It comprises four aluminium valves, four wheel electronics systems (wheel sensors), and four antennas, and a control unit (with an additional spare wheel monitoring system, five of each). The wheel electronics and valve are mounted on the rim. The radio receivers are located in the wheel well. For systems installed in series, the display unit is integrated in the instrument cluster.

Fig. 1 shows the individual components of the system:

  • Wheel electronics (1)
  • Wheel electronics with tire valve (2)
  • Retaining clips (3)
  • Antenna (4)
  • Control unit (5)

 

For retrofitted systems, a separate display unit is installed. During removal/mounting of the wheels/tires, the points mentioned previously must be observed. In the event of visible damage to the housing, or if the filter surface is dirty, the wheel electronics must be replaced.

 

The complete valve must be replaced when

  • the wheel electronics are replaced
  • the self-locking (Torx) fixing screw and/or the union nut of the valve is loose (do not retighten)
  • the contact points of the wheel electronics protrude by more than one millimeter

 

The wheel electronics and

  • tire valve can easily be assembled and mounted using Fig. 2:
  • Insert self-locking fixing screw (1) through the housing of the wheel electronics (2) and screw into the valve with two to three turns.
  • Slide valve (3) through the valve hole bore in the rim, put on spacer (4), and screw on union nut (5) until it lies against the spacer.
  • Insert mounting pin (7) into the radial bore of the valve, and tighten union nut with a torque of 3.5 – 4.5 Nm. Remove the mounting pin otherwise the tire will become damaged during further mounting.
  • Lightly press the wheel electronics into the rim well. The contact points must lie flat in the well. Then tighten the fixing screw with a torque
  • of 3.5 – 4.5 Nm.
  • Following tire fitting, screw on the valve cap (6).

Following a wheel/tire change, changing of the wheel position, replacement of the wheel sensor system, or a deliberate change to the tire pressure (e.g. when the vehicle is fully loaded), the new pressures are taken over by the TSS. For this, all of the tires must first of all be filled with the prescribed or specially selected pressure. By pressing the calibration button, the values are saved. The system then checks whether the pressures are realistic (e.g. the minimum pressure or the differences between left and right). If the wheels are transported in the boot of the vehicle concerned, for example for seasonal changing of the wheels, they are within range of the control unit. If the wheels being replaced have already been input into the system instead of the usual four (five with spare wheel), the control unit now receives eight or nine signals. In this case, the system reports that it is "not available".

 

The same thing can happen when unloaded wheels or the wheels of another vehicle (which also has a tire pressure monitoring system) are located in the vicinity. Please also make the customer aware that the system must then be re-calibrated again. Calibration of the series TSS is vehicle specific. Instructions for this can be found on the web pages of Beru.

PRACTICAL TIP

If the spare wheel is also to be monitored by the tire pressure monitoring system, following removal, it should be installed again in the precise location it was in before. Especially during an inspection or following a pressure test, for the BMW E60, E65, for example, it should be ensured that the tire valve is at the 9 o'clock position again following installation of the spare wheel. The receiver only detects signals from the transmitter in this position.

 

French vehicle manufacturers in particular use the SMSP system from Schrader. This is different in that it only has one radio receiver (antenna).

 

The position of the wheels is distinguished using colour identification on the valves:

  • Green ring = front left
  • Yellow ring = front right
  • Red ring = rear left
  • Black ring = rear right

 

Following tire fitting or replacement of a sensor, it may be necessary to code the sensors as a difference in position of the wheels may not be detected with just one antenna or because the wireless connection was interrupted. As the electronics in this system only measure the pressure every 15 minutes during vehicle standstill and only transfer the measured values once an hour to the control unit, for the coding, you need a diagnostic unit as well as a so-called "valve exciter".

 

It prompts the wheel sensor system to transmit the measured values to the control unit via radio.

Diagnostic units such as the Hella Gutmann mega macs 77 are also able to read out the fault memory and the actual values of the tire pressure monitoring systems, and to delete any fault codes.

 

Many vehicle systems additionally provide digital measured values as parameters to enable fast diagnosis. Parameters indicate the current status or setpoint and actual values of the component. In this section, you can, for instance, access information about the current tire pressure.

 

Additional information relating to maintenance and repair can be obtained in the vehicle information, depending on the vehicle model and system.

 

The respective test depth and variety of functions can be set out differently depending on the vehicle manufacturer and is dependent on the relevant system configuration of the control unit.

PRACTICAL TIP

Following removal of the wheels (e.g. during brake repairs) these must be re-installed in the location they were in originally. tire pressure monitoring system display faults may otherwise be the result (e.g. Renault Laguna 2).

 

For almost all tire pressure monitoring systems, transmission occurs in the frequency range of 433 MHz. This frequency range is also, however, used by radio devices, radio headphones, alarm systems, and garage door drives, for example. Please take this into account in the event of malfunctions with the tire pressure monitoring system. The current development is toward small active systems without batteries (transponder technology) which are just glued into the carcass or which are integrated into the tire. These systems operate in the 2.4 GHz range, which is not so susceptible to interference, and can record other information, such as road condition and wear state, in addition to temperature and pressure values.

Today, tire pressure monitoring systems are as common a part of vehicle equipment as ABS or the air-conditioning system.

 

For all of the monitoring technologies, one thing should not be forgotten. A tire pressure monitoring system does not correct the tire pressure itself and does not provide any information on the age or the tread depth of a tire. This means that in the future, too, it will be essential to regularly monitor the tire as the most important connection between the vehicle and the road.

Direct tire pressure monitoring system - example Mercedes-Benz W212 E350: Service notes

For the purpose of an example, the following information is illustrated using a Mercedes-Benz W 212 E350 featuring direct tire pressure monitoring system. This vehicle features sensors on all four wheels that forward the tire pressure to a superordinate system. The tire pressure monitoring system monitors the tire pressure using the data from the wheel speed sensors. If a pressure drop is identified on one of the tires, drivers are visually warned by a notification on the multi-function display indicating "tire pressure loss" on the instrument cluster. 

tire pressure illustration on the multi-function display

  • Switch on the ignition
  • Press the "Right arrow" system selection button on the steering wheel until SERVICE appears on the display (Figure 1).
  • Confirm the input with "OK".
  • Press the "Down arrow" button until "tire pressure" is shown on the display (Figure 2).
  • Confirm the input with "OK".

 

The display shows the current tire pressure of individual wheels (Figure 3). If the vehicle has not been moved for a prolonged period of time prior to the check, the display indicates "tire pressure monitoring appears after a few minutes of driving time".

Adjusting and saving the tire pressure in the system

In the following cases it is necessary to carry out basic tire pressure value setting in the system:

  • A tire pressure monitoring system warning message has been activated.
  • The tire pressure has been changed or adjusted.
  • tires or wheels have been installed in different positions or they have been replaced.
  • Battery disconnected or replaced.

 

The following warning messages appear on the display:

  • "Correct tire pressure". The tire pressure of at least one tire is too low and must be re-inflated from time to time
  • "Check tire pressure". The tire pressure at one or more tires has dropped significantly
  • "Caution: tire faulty". The tire pressure at one or more tires has suddenly dropped significantly

Initialisation process

Park the vehicle in a safe location and engage the parking brake.

  • Check the tire pressure of all four wheels as per manufacturer instructions and correct, if necessary.
  • Switch on the ignition.
  • Press the "Right arrow" system selection button on the steering wheel until SERVICE appears on the display.
  • Confirm input with "OK".
  • Press the "Down arrow" button until the "tire pressure monitoring system active"notification appears on the display.
  • Confirm input with "OK".
  • "tire pressure OK now?" shown on the display (Figure 4).
  • Select "YES" and confirm.
  • "tire pressure monitoring system restarted" appears on the display.

 

After a few minutes of driving the system checks the new tire pressures and subsequently saves them as the new reference values. Alternatively it is possible to adjust the basic setting using a suitable diagnostic unit. The tire pressure monitoring system automatically detects this following the calibration process.

Maintenance information

In this vehicle model the vehicle manufacturer's recommended tire pressures have been listed on a sticker in the tank flap or in the operating manual. If an incorrect tire pressure is set and activated, the system will monitor the incorrect pressure!

 

The tire pressure monitoring system function may be impaired or delayed in the following cases.

  • Snow chains have been fitted to the vehicle
  • Vehicle is being driven on unsurfaced roads
  • Driving with a heavily loaded trailer
  • Sporty driving style, severe acceleration or braking on routes with many corners
  • One-sided loading as a result of having overloaded one side of the vehicle

Important!

With regard to this, please always observe the respective maintenance and repair notes provided by the vehicle manufacturer.

Indirect tire pressure monitoring system - example: Mazda CX-5: Service notes

The following information is illustrated using a Mazda CX-5 featuring indirect tire pressure monitoring system as an example. The system records the tire pressure of all four wheels. The ABS control unit determines the tire pressure on the basis of the data from wheel speed sensors. Drivers are visually and audibly warned if a drop in pressure is detected at one of the tires. The system must be initialised with the prescribed tire pressure to guarantee the system operates correctly.

Adjusting and saving the tire pressure in the system

Re-initialise the system in the following cases.

  • tire pressure has been corrected.
  • One of the tires has been replaced.
  • The position of tires on the vehicle has been changed.
  • The ABS control unit has been replaced or disconnected.
  • The battery has been disconnected or replaced.
  • The tire pressure monitoring system warning light is on.

Initialisation process

Park the vehicle in a safe location and engage the parking brake.

  • Check the tire pressure of all four wheels as per manufacturer instructions and correct, if necessary.
  • Switch on the ignition.
  • Press the SET button until the TPMS warning lamp on the dashboard flashes twice and an audible warning is output (Figure 5).
  • "tire pressure monitor initialised" appears on the display (Figure 6).
  • Subsequently take the vehicle for a test drive to complete the process.

Maintenance information!

In this vehicle model the manufacturer's recommended tire pressures have been listed on a sticker on the driver's side B-pillar or in the operating manual. The principle to calibrate winter tires is identical as this vehicle does not feature TPMS sensors.

Causes of failure

Warning messages may be output in the following cases because the system may identify changes to the tire condition.

  • A tire pressure value significantly above the prescribed value has been set
  • The wheel and tire combination does not meet vehicle manufacturer specifications
  • Use of a space saver spare wheel or snow chains
  • Aggressive driving style, severe acceleration or braking on routes with many corners
  • One-sided loading as a result of having overloaded one side of the vehicle

Important!

With regard to this, please always observe the respective maintenance and repair notes provided by the vehicle manufacturer.

EU LEGISLATION ON tire PRESSURE MONITORING: BACKGROUND INFORMATION

On March 10, 2009 the European Parliament in Strasbourg officially adopted a proposed directive (EC no. 661/2009) put forward by the Commission to make motor vehicle homologation easier in Europe. In this process, the directive also included a mandatory introduction of previously mentioned technologies including a tire pressure monitoring system (TPMS). "Category M1/M1G vehicles shall be equipped with an accurate tire pressure monitoring system capable of outputting an in-car warning to the driver when a loss of pressure occurs in any tire, in the interests of optimum fuel consumption and road safety. The implementation process was carried out in stages: from November 2012 a tire pressure monitoring system has been mandatory in all newly homologated vehicle types and this has applied to all newly registered vehicles from November 2014.