Position finding, function - GF82.95-P-3000GQU

MODEL 164.1 with CODE (359) TELE AID emergency call system as of model year 2009/Modification Year 2008 model refinement package 

MODEL 164.8 with CODE (359) TELE AID emergency call system as of model year 2009/Modification Year 2008 

MODEL 251.0 with CODE (359) TELE AID emergency call system as of model year 2009/Modification Year 2008 

MODEL 251.1 with CODE (359) TELE AID emergency call system as of model year 2009/Modification Year 2008 

Position finding function requirements 

• Emergency call system authorized and operating properly
• Proper communication with ESP control unit (N47-5)
• An emergency call system control unit (N123/4) communication module authorized for the corresponding vehicle-related service is configured ex-factory with the telephone number of the corresponding service provider

General position finding 

For position finding, emergency call system control unit requires the Global Positioning System (GPS), a satellite-supported positioning system. It is available worldwide. The GPS satellites permanently transmit time and position data (longitude and latitude). GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). Relocating with GPS (after interruption of satellite reception) may require several minutes (up to 20 min when emergency call system control unit is commissioned). Basic position finding runs parallel to GPS position finding.

The position finding function consists of the following subfunctions:

• Function sequence for GPS position finding 
• Basic position finding function sequence 

GPS position finding function requirements 

• Status "Circuit 15R ON" or one of the following vehicle-related services actuated:
  • Emergency call (E-Call) manual or automatic, including police emergency call number "911"
  • MB-Info call
  • Breakdown assistance (Roadside Assistance)
  • Vehicle tracking
  • Vehicle remote door unlock
• No fault in GPS antenna systems and signals from at least 3 GPS satellites

Function sequence for GPS position finding 

The GPS receiver integrated into the emergency call system control unit receives the GPS signals from the GPS antenna (A2/93a6) over the following path:

• Direct line
• GPS antenna splitter (A2/5), with code (512) COMAND APS with DVD changer, and direct line

The GPS signals are used by the emergency call control unit to calculate the current vehicle position (receiver).

In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

Basic position finding function requirements 

• Status "Circuit 15R ON"

Basic position finding function sequence 

For basic position finding, the emergency call control unit requires the following information:

• Wheel speed signals
• Distance traveled data
• Direction of travel data (forwards or backwards)

The wheel speed signals are detected by the following rpm sensors:

• Left front rpm sensor (L6/1)
• Right front rpm sensor (L6/2)
• Left rear rpm sensor (L6/3)
• Right rear rpm sensor (L6/4)

The wheel speed signals from the rpm sensors are received by the emergency call system control unit over the following path:

• Direct line
• ESP control unit
• Engine compartment CAN
• Central gateway control unit (N93)
• Diagnostic CAN

The distance traveled data is received by the emergency call system control unit from the instrument cluster (A1) in the following way:

• Interior CAN
• Central gateway control unit
• Diagnostic CAN

The emergency call system control unit receives the data on the direction of travel (forwards or backwards) from the central gateway control unit over the diagnostic CAN.

After this the emergency call system control unit uses the distance traveled, the vehicle alignment and the direction of travel to calculate the vehicle position (degree of longitude and degree of latitude) at any given time.

Error during position finding 

Basic position finding is falsified when a vehicle rolls backwards with "circuit 15 OFF" (ignition switched off) or if it is transported somewhere. In both instances, the deviation is automatically corrected by the navigation processor integrated into the emergency call system control unit when it receives GPS data.

	Electrical function diagram for position finding, function	Model 164	PE82.95-P-2070-97MAA
		Model 251	PE82.95-P-2070-97RAA
	Instrument cluster, component description	A1	GF54.30-P-6000GM
	ESP control unit, component description	N47-5	GF42.45-P-5118GM
	Central gateway control unit, component description	N93	GF54.21-P-4170GM
	Emergency call system control unit, component description	N123/4	GF82.95-P-3212GQU