1992 300SD W140

Had the ABS light come on within a few metres of driving. Then would come on everytime the car was started until I disconected the battery. Then would come on again within a few metres of driving, along with hard / rough steering.

-Brake light switch replaced with MB OE. No change.
-Swapped ABS module & Base module with known working one from working car. No change.

-Scaned pin 6 (ABS Module) with pulse counter and got these codes:
DTC 2 Left front axle vehicle speed sensor (L6/1)
DTC 7 Right front axle solenoid valve (A7/3y2)
DTC 9 No Fault on chart for my year / model, but on JimF sites for newer models it refers to: Right rear axle solenoid valve (A7/3y4)
DTC 11 Solenoid valve relay (A7/3k1)

-Changed Left Front sensor & ABS light went away for about 10min of driving, then came back. The hard steering started first, then the ABS light came on.

I'm left to think my issue is this Solenoid Valve Relay (A7/3k1), can anyone tell me where it is. I've searched online & alldata and just can't figure out which one it is.

Much apprechiated.