Possible causes, elimination, notes

Actual fault: ABS solenoid valve faulty. 

The System Tester 2 can be used to check the function of the ABS solenoid valves via the Drive links menu, sub-menu Maintain pressure and Reduce pressure. 

If the control module or ABS solenoid valve is damaged, the complete hydraulic unit with integrated control module must be replaced.

Important:  Before replacing the hydraulic unit, check whether:

• ground is connected to control module connector PIN 16 (from ground point 2) and PIN 19 (from electronics ground). The locations of the ground points are shown on the wiring diagram Ground points.
• plus (vehicle voltage) is connected to control module connector PIN 17 and PIN 18.
• Use the System Tester 2 to test the function of the ABS solenoid valves via the Drive links menu (reaction at the front left, front right, rear left and rear right wheels).

  If the reaction is not OK,  check the hydraulic allocation (text below).

  Allocation test using example of left front wheel: 

  In the Drive links menu, sub-menu Reduce pressure, front left,  the left front wheel must alternately lock up and then rotate freely.

  The allocation is wrong if the activated wheel does not alternately lock up and rotate freely again, but a different wheel  does this instead.

• The hydraulic unit must be replaced if the aforementioned drive link test is not OK but the hydraulic lines are not swapped.