Road Speed Signal DDE 4.0

The vehicle's current road speed is signalled to the DDE control module by the ABS/DSC control module.

The road speed serves as a measurement variable for the following functions:

• Control condition for air conditioning system
  
• Limit volume calculation
  
• Injection volume calculation
  
• vehicle speed control
  
• Gear recognition
  
• Idle speed control
  
• Electric fan control
  

Troubleshooting

If the signal is recognized as being faulty or the road speed as too high or if the injection volume and engine speed infringe the plausibility, a fault code is stored and a substitute value is output.

Consequences:

• Deactivation of vehicle speed control
  
• Deactivate A/C compressor