Central gateway control unit, component description - GF54.21-P-4170GM

MODEL 164.1 as of Model Year 09/Modification Year 08 model refinement package

MODEL 164.8, 251.0/1 as of Model Year 09/Modification Year 08

Shown on model 164.1

Fig 1: Identifying Central Gateway Control Unit Component - Shown On Model 164.1

Courtesy of MERCEDES-BENZ USA

Location

The central gateway control unit is mounted onto the vehicle floor below the driver seat.

Task

The central gateway control unit has the following tasks:

Gateway
Variant coding
Data container
Reverse gear signal generation

Gateway

The central gateway control unit serves as an interface between the following databus systems:

Diagnostic CAN
Interior CAN
Engine compartment CAN

Diagnostic CAN

The primary purpose of the diagnostic CAN is to allow connection of an external diagnostic unit. This is used to diagnose control units. This is achieved via diagnosis request messages which the diagnostic unit sends to the control unit in question.

The central gateway control unit responds to these diagnosis request messages with diagnosis response messages.

Interior compartment CAN:

The central gateway control unit routes the information from the control units connected to the interior CAN to the control units connected to the engine compartment CAN by placing the information on the engine compartment CAN or establishes a connection between the diagnostic CAN and interior CAN for diagnostic purposes.

Engine compartment CAN:

The central gateway control unit routes the information from the control units connected to the engine compartment CAN to the control units connected to the interior CAN by placing the information on the interior CAN or establishes a connection between the diagnostic CAN and engine compartment CAN for diagnostic purposes.

The functional gateway messages are sent, irrespective of the circuit status, over the interior CAN. By contrast, the control units on the engine compartment CAN only send at circuit 15 ON. The gateway messages are therefore only transmitted on the engine compartment CAN when circuit 15 is on. Routing from the interior CAN to the diagnostic CAN is only possible with an active interior CAN.

Variant coding

The central gateway control unit sends information (e.g. model series and national version) over the interior CAN, engine compartment CAN and diagnostic CAN to the corresponding control units.

Data container

The data container in the central gateway control unit is a mobile data memory.

Data specific to vehicle, test site or control unit are stored in the data container within the cycle.

These data can be used in the subsequent tests for test sequence control. The total size of the data memory is 128 bytes.

Reverse gear signal generation

The "Reverse gear engaged" signal is sent irrespective of the transmission version over the interior CAN by the central gateway control unit. The reverse gear signal is generated by evaluating the "Transmission selector lever" over the engine compartment CAN.

	Wiring diagram of central gateway control unit	Model 164	PE54.21-P-2124-99MAA
		Model 251	PE54.21-P-2124-99RAA