Speed, wire from ABS: Notes

WARNING: This page is about a different car, the 2001 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Speed, Wire From ABS - Control Module Communication Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Identifying Speed, Wire From ABS - Control Module Communication Circuit Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The 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:

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.