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Vehicle speed

Vehicle speed



The ABS control module sends a vehicle speed signal to pin 39 of the Trionic ECM. The signal is a square-wave which varies between 0 V and Batt+ 29 times/ wheel rotation. This speed signal is used to:


decide 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 limiting (by limiting the boost pressure at 230 km/h)

If there is no speed signal, the above functions do not occur and the boost pressure, on cars with manual transmission, is limited.