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

GF40.15-P-2001RE Detect seeping pressure loss, function
- with CODE (475) Tire pressure monitor (Siemens)
- as of 1.6.05 up to model year 08


Function

Tire pressure monitoring (TPM) assists the driver in constantly monitoring the correct tire inflation pressure.

Every tire loses air by diffusion over the course of time. To increase comfort, the driver receives a timely message that his tire pressures need correcting from the TPM system. The warning is issued directly after the end of the trip.

Temperature compensation

A temperature increase always leads to an increase in pressure in the tire. The temperature-specific pressure change in the tire is calculated in the TPM [RDK] control unit (N88) and is taken into account by the system. Tire temperature changes do not result in incorrect warnings.

Soft warning

The warning is issued for a pressure loss of 0.25 bar relative to the stored filling pressure. The warning threshold is has an upper limit of 0.2 bar below the filling pressure.

Cancellation of warning:

^ Warning threshold is no longer dropped below
^ Filling detection was successful
^ Manual reactivation of the TPM system was carried out

Checking the warning condition while driving

If the warning threshold is dropped below for a period of 12 minutes a warning signal is stored in the memory of the TPM [RDK] control unit and is displayed in the instrument cluster (A1) upon ignition "OFF" (circuit 15).

Hard warning

The hard warning informs the driver of a distinct, safety-relevant pressure loss while driving. The warning complies with the requirements of legislation in the USA.

Parameters for a hard warning:

^ A warning is issued for a pressure loss of 20 % or 0.5 bar relative to the stored filling pressure.
^ The lower limit of the warning threshold is the minimum pressure (1.5 bar).
^ Temperature compensation for hot tires is limited at a temperature of 40 degrees C over the ambient temperature. The warning threshold remains constant.
^ The warning threshold is has an upper limit of 0.2 bar below the filling pressure.

The warning is suppressed during filling detection.

The tire pressure monitor warning lamp (A1e66) in the instrument cluster is activated at the same time as the "hard warning". It does not go out until the TPM system is reactivated.

Cancellation of warning

When the engine is switched back on after a hard warning the tire pressure monitor warning lamp is initially reactivated. The warning is canceled when filling detection or a manual reactivation is successfully carried out.