There are two possible ABS units in the 928.

The 928.618.118.00 which is the old style used in cars prior to 1990,

and the 928.618.120.01 which has PSD combined with ABS. The difference can easily be seen, it has an extra row of pins.

The 928.618.120.01 has diagnostic features and can be operated from a handheld OBD tester or from a computerized tester.

Here's a screenshot from a ABS/PSD.

55 Free 37 Ground, ABS solenoid valves, front left + rear axle 19 Operation of ABS solenoid valve, front left
54 Free 36 Free 18 Free
53 Speed sensor output at front right for RDK control unit 35 Operation of instrument cluster: PSD off 17 Monitoring, voltage supply for ABS solenoid valves
52 Electronics ground 34 Signal from lateral acceleration sensor 16 Speed sensor output at front right for RDK control unit (*)
 
51 Free 33 Free 15 Voltage supply (+5v) for acceleration sensor
50 Signal, speed sensor at front left 32 Free 14 Free
49 Free 31 Pump motor monitoring (hydraulic unit) 13 Free
48 Ground, shield, speed sensor at front left 30 L-wire from diagnosis 12 Speed sensor output at rear left for RDK control unit (*)
47 Signal, speed sensor at front right 29 Brake light switch 11 Voltage, terminal 30
46 Ground, shield, speed sensor at front right 28 Free 10 Speed sensor output at rear right for RDK control unit
45 Signal, speed sensor at rear left 27 +D (Terminal 61 / charge) 9 Ground of acceleration sensor
44 Ground, shield, speed sensor at rear left 26 Free 8 Free
43 Signal, speed sensor at rear right 25 Free 7 Operation of valve relay on hydraulic unit
42 Ground, shield, speed sensor at rear right 24 Operation of ABS warning lamp 6 Free
41 Free 23 Monitoring of supply voltage for lock solenoid valve 5 Operation of pump motor relay on hydraulic unit
40 Indicator lamp green for PSD function 22 Operation of ABS solenoid valve, front right 4 K-wire from diagnosis
39 Free 21 Operation of transverse lock solenoid 3 Ground, ABS solenoid valve, front right
38 Free 20 Voltage for valve and motor relays on hydraulic unit 2 Operation of Rear-axle valve solenoid
        1 Voltage, Terminal 15
           
(*) Additionally to vehicle speed. Pin 16 (front left) on mod. 1991/1992 and Pin 12 (rear left) as of mod. 1993

 

 

ABS ecu location on a GTS