For the brake light switch, the electrical capacity of the contact points is not sufficient, and therefore, they may fuse. If this problem is left unattended, (1) the brake lights may remain on, causing the brake light switch to overheat, and the wiring might melt, which, in the worst case, could lead to smoke emission and/or a fire, (2) the brake lights may fail to illuminate, which might make it impossible to shift the shift lever from 'P' position.