ABS malfunction

Periodically, the ABS light came on, while the actual ABS disappeared. Since I noticed, this problem hasn’t bothered me much - the light has been on just periodically, but for the last 2 weeks it has been on more often than it has gone out.
Well, I choose the time and go to an auto electrician (as it turned out later, I could handle it myself).
Preliminary googling showed the following possible causes of the malfunction and diagnostic methods:
1. Sensor breakage / sensor malfunction.
2. Oxidation of ABS connector contacts.
The first reason is diagnosed by "ringing" contacts. Sensor 4, respectively, it is necessary to ring 4 times. One contact rang, the norm, they scored on the rest, I decided to check the block right away - and yes, indeed, the oxidation of the contacts on the face (see photo). Eliminate, rejoice. It remains only to figure out how to prevent this from happening.

This photo shows where the water comes from in the frame. It is taken from the wiring harness from the milestone. Before they began to fiddle with the tourniquet, the pad remained completely dry!

But actually the culprit of the problem: traces of oxidation are clearly visible in the photograph.

Source: https://www.drive2.ru/l/783895/