Hello Danilo,
on your 840, K10 shoud be Servotronic, not ABS
I've a control lamp in the cokpit, yellow-on at startup and off when running.
I've connectors in the empty emplacement at positions 2,5,6 and 8
:-----------------
3: : - : :9
:-----------------
2: | : | : - :8
:-----------------
1: : : :7
:-----------------
In ETK, i've found 61 35 8 365 325 Relay ABS/ASC+T but connectors didn't correspond
In ETM, model 1993 didn(t use this emplacement.
But in ETM model 1992, this emplacement is used for ABS. (my 850 was buid may 1992)
Sorry for my poor english