Speed, Lead 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 a square wave that varies between 0 V and B+, 29 times per wheel revolution.

This speed signal is used to:
- determine, on manual gearboxes, which gear is used at the moment. This allows torque limitation in gears R and 1 and activation of the fuel shut-off in gears 2, 3, 4 and 5.
- activate speed limitation by limiting the maximum mass air flow/combustion at 240 km/h.
- prevent adaptation of idle speed control when the car is moving.

Diagnostics
- If there is no speed signal, diagnostic trouble code P0502 will be generated.
- The speed (bus from MIU) is used as a substitute value.

System reaction to a fault
Cruise control is blocked.