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Speed, bus from TC/ABS

Speed, bus from TC/ABS



TC/ABS control module sends the bus message "Wheel speed, front right, XXX km/h” via the P-bus to the Trionic control module pins 19 and 66. This 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 for B235E and 250 km/h for B235R.


Diagnostics


• If the speed message is missing, DTC P0502 is 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.