GF40.15-P-2001SX Detect Seeping Pressure Loss, Function

GF40.15-P-2001SX Detect Seeping Pressure Loss, Function
MODELS 221 with CODE (475) Tire pressure monitor (Siemens)

Function
The tire pressure monitor (TPM) assists the driver in monitoring the correct tire inflation pressure.
Every tire loses air by diffusion over the course of time. As a comfort function the driver receives in good time information on the due correction of his tire pressures from the TPM system. The warning ensues immediately after the end of the journey.

Soft warning
The warning takes place in a temperature-compensated manner at a pressure loss of 0.25 bar compared with the stored filling pressure. The warning threshold is limited upwards to 0.2 bar under the filling pressure.

Cancelation of the warning:
- The warning threshold is no longer dropped below
- Filling detection was successful
- Manual reactivation of the TPM system carried out

Parameters for hard warning:
- The warning ensues at a pressure loss of 20% or 0.5 bar compared to the stored filling pressure.
- The warning threshold is limited downwards to the minimum pressure (1.5 bar).
- The temperature compensation with hot tires is limited at a temperature of 40°C above the ambient temperature. The warning threshold remains constant.
- The warning threshold is limited upwards to 0.2 bar under the filling pressure.

Note: The warning is suppressed during filling detection.

Temperature compensation
A temperature increase always leads to a pressure increase in the tire. In the TPM [RDK] control unit (N88) the temperature-dependent pressure change in the tire is calculated and taken into account in the TPM system strategy. A temperature change in the tire does not lead to erroneous warnings.

Checking the warning condition while driving
If the warning threshold is dropped below for a time of 12 minutes, a warning signal is stored in the memory of the TPM [RDK] control unit and displayed in the instrument cluster (A1) with the ignition "OFF" (circuit 15).

Hard warning
While driving, the hard warning points out a significant and safety-relevant pressure drop to the driver. The warning corresponds to the requirements of the USA legislation.
The tire pressure monitor warning lamp (A1e66) in the instrument cluster is actuated in parallel with the hard warning. It goes out after the TPM system is reactivated.

Cancelation of the warning:
With an ignition restart following a hard warning the tire pressure monitor warning lamp is actuated again first. The warning is canceled by a successful filling detection or manual reactivation.