Centrale gateway module

The central gateway module transmits signals and messages on the following bus systems:

• Serial diagnostic cable
  
• BYTEFLIGHT
  
• PT-CAN (Powertrain CAN)
  
• System K-CAN (body CAN system)
  

The connection between the diagnosis system and the vehicle is exclusively via the central gateway module. The Central Gateway Module is connected by means of the OBD (on-board diagnosis) connector via a serial copper lead (= diagnosis lead). The diagnostic head of the BMW diagnosis system is connected at the OBD plug. The BYTEFLIGHT fibre-optic bus is assigned to the safety system (e.g. airbags). The PT-CAN bus is used for engine-related functions and the System K-CAN bus for body-zone functions.

Wake-up and Sleep conditions:

• The central gateway module can 'go to sleep' (switch off the internal power supply) if
  
  • the PT wake-up line signal is not ”High”
    
  • there are no wake-up signals present on the BYTEFLIGHT fibre-optic bus
    
  • the diagnostic cable is not connected to ground
    
  • there is no activity on the System K-CAN bus
    Sleep mode readiness is initiated simultaneously for all busses if all nodes of all the bus systems connected to the central gateway module indicate readiness, the PT wake-up line signal is not at ”High” and the diagnosis lead is not being operated externally. The central gateway module prevents individual busses on which all nodes are ready to switch to Sleep mode from switching to Sleep mode if at least one node an another bus is not ready for Sleep mode.
    
• The central gateway module is wakened (internal voltage switched on) if
  
  • the PT wake-up line signal is ”High”
    
  • a wake-up signal is detected on the BYTEFLIGHT fibre-optic bus
    
  • the diagnostic cable is connected to ground
    
  • a message is received on the K-CAN SYSTEM
    
  • a power-down reset is initiated by Terminal 30
    

The central gateway module wakes up the K CAN SYSTEM bus, PT CAN bus via the wake-up line and the BYTEFLIGHT bus if one of the busses is woken up.

Note:

The control modules on the PT-CAN bus have a separate wake-up line. The control modules on the PT-CAN bus are woken up by a High signal on the wake-up line. The High signal at the wake-up line is a minimum of 5 Volts.

The Car Access System control module operates the wake-up line as follows: when ”Terminal 15 on” a High signal is applied to the wake-up line. If the bus is in Sleep mode and ”Terminal 15 Off” changes to ”Terminal 15 On”, the Car Access System transmits a wake-up signal. This wake-up signal is always adopted by the Central Gateway Module. The signals ”Wake Up” and "terminal 15 on" are distinguished by reading the CAN message with the Terminal 15 signal.

• Wake-up line signal ”High” and ”Terminal 15 On” means ”Vehicle being driven”
  
• Wake-up line signal ”High” and ”Terminal 15 Off” means ”Wake Up”
  

Operational test of the Central Gateway Module

The subsequent operational test indicates whether the central gateway module is operating properly.

• Transmission PT-CAN to K-CAN SYSTEM (precondition: running engine): If the transmission is OK, the engine speed is shown in the instrument cluster. (Signal path: Digital Engine Electronics - PT CAN - Central Gateway Module - K CAN SYSTEM - Instrument Cluster).
  
• Transmission BYTEFLIGHT to PT-CAN (requirement: running engine): if the transmission is OK, the individual stages P, D, N and R are enabled when the gear selector lever is operated. (Signal path: Steering Column Switch Center - BYTEFLIGHT - Safety Information Module - BYTEFLIGHT - Central Gateway Module - PT CAN - Electronic Transmission Control). For safety reasons, there is a serial cable from the steering column switch center to the electronic transmission control. The aim of this test is to ensure that the following fault memory entries are not present in the steering column switch center:
  
  • 94DE gear selector switch: Bus fault
    
  • 94DF gear selector switch: Bus fault and serial wire fault
    
• Transmission BYTEFLIGHT to K-CAN SYSTEM (requirement: ignition on): if the transmission is OK, the wiper is activated when the wiper switch is operated. (Signal path: Steering Column Switch Center - BYTEFLIGHT - Safety Information Module - BYTEFLIGHT - Central Gateway Module - K CAN SYSTEM - Wiper Module).
  

If the above operational test is OK, then there is high probability that the central gateway module is in proper working order.