Voltage Supply and Main Relay DDE 4.1

Function

The voltage supply to the DDE control units takes place in the following steps:

• At ignition ON, voltage is applied via terminal 15 to the DDE master control unit
  
• The DDE master control unit switches both DDE main relays via S_HR
  
• The DDE main relay 1 switches terminal 30 via U_HR to the DDE master control unit
  
• The DDE main relay 2 switches terminal 30 via U_HR to the DDE slave control unit
  

Troubleshooting

The following faults are monitored in the voltage supply system:

• Fault code 2800 (master), 2801 (slave): Voltage supply to DDE control unit exceeded/below specified value
  
• Fault code 3510 (master), 3511 (slave): DDE main relay switches too early or too late