Tire pressure monitor function - GF40.15-P-0001MCU

MODEL 451.3 /4 

Function requirements 

• Circuit 15 On
• Tire pressure monitor system functional

General information 

The tire pressure monitor assists the driver when checking the tire inflation pressure and thus serves active safety.

The Tire pressure monitor monitors the air pressure in the individual tires. A previously stored tire pressure is used as a comparative value. In the event of a relevant pressure loss the driver is warned via the tire pressure monitor warning lamp. The tire pressure measuring range extends from p = 0 and 5.5 bar.

The tire pressure monitor is made up of the following component functions: 

• Tire pressure sensing
• Warning display
• Manual restart

Tire pressure sensing 

The TPM [RDK] control unit is permanently operational. Each time the CAN wakes-up the TPM [RDK] control unit performs a re-initialization. While driving, the TPM [RDK] system continuously monitors the tire pressure of all rotating wheels (with circuit 15 Off for a further t = 19 min). With new wheels or a parking time in excess of t > 19 min, the individual wheel detection and axle assignment must be completed first via the TPM wheel sensors. The TPM wheel sensors transmit data telegrams every t = 60 s while driving.

These data telegrams contain the pressure, tire pressure temperature, individual serial number and status information (manufacturer, direction of rotation, operating mode etc.). The data are conveyed via two-way radio to the TPM [RDK] control unit. In addition the TPM [RDK] control unit takes into account the outside temperature and the vehicle speed for the tire pressure determination. These data are provided via CAN from the instrument cluster.

Warning indicator 

A warning is issued when a relevant loss of pressure has been detected in at least one of the tires.

The driver receives the feedback over the tire pressure monitor warning lamp. The warning is issued without any position data.

Manual restart 

The tire pressure monitor button in the cockpit switch panel can be used to reactivate the tire pressure to be monitored.

When the tire pressure monitor button is pressed the tire pressure at that time, as long as it is in the permissible limits, is stored in the internal memory of the TPM [RDK] control unit and used as a reference pressure.

A manual restart is displayed by the tire pressure monitor warning lamp flashing 3 times. The warning lamp request is sent over CAN from the TPM [RDK] control unit.

A manual restart must be carried out for each change in tire inflation pressure, when replacing a wheel or a wheel sensor as well as when replacing the TPM [RDK] control unit.

	Tire pressure monitor (TPM [RDK]) location of components		GF40.15-P-0001-06MCU
	Tire pressure monitor (TPM [RDK]) block diagram		GF40.15-P-0001-07MCU
	Wiring diagram for tire pressure monitor control unit		PE40.15-P-2101MCU
	Instrument cluster, component description	A1	GF54.30-P-6000MCU
	Wheel sensor, component description	A69/1, A69/2, A69/3, A69/4	GF40.15-P-5126MCU
	Outside air temperature sender component description	B14	GF83.57-P-4000MCC
	SAM control unit, component description	N10/10	GF54.21-P-4157MCU
	Tire pressure monitor control unit, component description	N88	GF40.15-P-5124MCU
	Cockpit switch group, component description	S6/1	GF54.25-P-4300MCU