Wheel sensor, component description - GF40.15-P-5126SX

MODEL 216.3, 221.0 /1 with CODE (475) Tire pressure monitor (Siemens) up to Model Year 8

MODEL 216.3, 221.0 /1 with CODE (470) Tire pressure monitor (base) up to Model Year 8

MODEL 216.3 with CODE (494) USA version up to Model Year 8

Location

Fig 1: Identifying Wheel Sensor Components

Courtesy of MERCEDES-BENZ USA

Design

Fig 2: Identifying Design Of Wheel Sensor

Courtesy of MERCEDES-BENZ USA

The TPM wheel sensors are screwed securely inside the rim.

Each TPM wheel sensor is connected to the filling valve via the mounting screw and together with this forms an assembly unit. This assembly unit is attached to the rim flange with the counternut.

A wheel sensor consists of the following components:

Pressure sensor
Temperature sensor
Acceleration sensor
High frequency (HF) transmitter
Sensor battery for voltage supply

The TPM wheel sensor can only be replaced as a complete assembly unit

Task

The task of the TPM wheel sensors is the pressure/temperature and acceleration measurement. The following data are transmitted via the integrated high frequency (HF) transmitter at specific intervals:

Tire interior pressure
Tire temperature
Wheel acceleration
Individual sensor ID
Condition of sensor battery

Function

Each TPM wheel sensor transmits a data protocol to the central TPM [RDK] antenna (A2/97). An identification number (ID) unique to the electronics is stored in each TPM wheel sensor. The TPM [RDK] control unit (N88) assigns (after a learning phase) the ID to the wheels fitted to the vehicle. A mounted, fully adequate spare tire with TPM wheel sensor is detected and managed after driving for a few minutes.

Following a wheel change or after replacing a TPM wheel sensor the new TPM wheel sensor with new ID (e.g. after assembling the spare tire) is detected as quickly as possible and monitored as new ID, even if the TPM [RDK] control unit is still receiving the wheel identifier used previously. Wheel identifiers not received from the vehicle do not cause an erroneous warning.

The TPM wheel sensors are identified depending on national version and transmit their data on different frequencies:

315 MHz, detectable by the frequency detail and an unfilled square symbol
433 MHz, detectable by the frequency detail and square symbol filled with a line grating

While driving the TPM wheel sensors transmit three data messages every 60 3 seconds. The absolute pressure, the wheel temperature, acceleration, ID and status information (manufacturer, frequency, pressure range etc.) are transmitted in these data packages. The measuring range of the TPM wheel sensor covers between 0 and 5.5 bar (relative pressure).