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Vehicle speed

Vehicle speed



The ABS electronic control module sends a speed signal to pin 39 of the Trionic electronic control module. This signal is a square wave which varies between 0 V and B+ 29 times per wheel revolution. This speed signal is used to:


determine which gear is engaged at the time

activate the SHIFT UP lamp (does not apply to 5th gear)

limit the boost pressure in Reverse, 1st and 2nd gears

activate fuel shut-off in 3rd, 4th and 5th gears

activate speed limitation (by limiting the boost pressure at 230 km/h)

prevent adaptation of idle speed control when the car is in motion. In the absence of a speed signal the above functions are not performed and, on cars with a manual gearbox, boost pressure is limited.