BROKEN OR DAMMAGED WIRING

Just have in mind that most cars have hundreds of meters of wiring in them! If one is broken or damaged it can be like searching for a needle in a haystack.
These types of car electrical problems may be very hard to find, even painstaking. Usually involves taking of plastic trimming, plastic covers, wire looms, connectors etc. On this part, a huge amount of patience is necessary.
Broken or damaged wiring can cause problems that may be attributed to other things (like sensors, switches, relays or else). This can easily send you on a wild goose chase and cause unneeded expenses.
When solving this problem, some knowledge of the car electric installation will come in handy. There are also tools that can help with these car electric problems (detectors of broken cables for instance).
It can be solved, if with nothing else, then with bypassing parts of the installation that are broken or damaged.