Quote:
Originally Posted by cooljess76  The problem is that the resistor on the dimmer switch is too weak and blows before the fuse does, thus costing more money to replace a switch rather than replacing a fuse. It appears to be a design flaw, but like many things, can be made to work better. |
More likely it was a design decision. At the time, BMW was still installing some controls that weren't protected against overloads and short circuits. They were likely aware of the limits of the rheostat they used but probably decided a short or overload in that circuit was going to be rare. I suspect they had not anticipated some of the wear and tear the wiring would experience, from normal use, repairs and retrofits.
BTW, the fuse you are thinking about is there to protect the wiring, not the consumers that are connected to it, such as the rheostat.