Speed signal

The input of the driving speed signal (V-signal) is required in the DME control unit for several functions.

• It serves the purpose of maintaining the programmed top speed. Once this is achieved, the mixture and ignition are varied and individual ignition and injection signals masked out as required thus ensuring smooth shut-down.
  
• On vehicles with the air conditioning switched on compressor activation is interrupted up to a driving speed of 13 km/h when accelerating under full load.
  
• Idle speed control is activated at a driving speed signal > 0 km/h, i.e. the idle speed has a fixed value that is normally just above the engine speed when the vehicle is stationary.
  
• The idle speed is controlled accordingly if the driving speed is 0 km/h. However, it is still corrected by the A/C signal, drive stage information on automatic vehicles and the light switch input.
  
• Poor road surfaces are also detected by means of the speed signal. The smooth-running monitoring function is deactivated if a poor road surface is detected.