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Speed, wire from ABS (TC/ABS)

Speed, wire from ABS (TC/ABS)





The ABS or TC/ABS control module sends a speed signal to pin 64 on the Trionic T7 control module. The signal is square wave and varies between 0V and B+ 29 times per wheel revolution. The wheel speed signal is used to:


prevent adaptation of idle speed control when the car is moving.

on manual gearboxes, determine which gear is currently being used. This makes it possible to limit torque in gears R and 1 and activate fuel shut-off in gears 2, 3, 4 and 5. Control of the SHIFT UP lamp also depends on the current gear.

activate speed limitation, which is achieved by limiting the maximum air mass/combustion at 240 km/h.




Diagnostics


If the speed signal is missing, diagnostic trouble code P0502 will be generated.

If the speed value is implausible, diagnostic trouble code P0501 will be generated.


System reaction to a fault


Speed (bus from MIU) used as substitute value.

Cruise control blocked.