We have a 2002 Mercedes sprinter in my work with a couple of mystery electrical problem. The first one is that when the hazard warning lights are left on for no more the 5 minutes, the battery appears to drain. The second, which has just occurred recently is that the break lights do not light up when the brake pedal is pressed. The mechanic we use has tested the battery and says it's fine. The brake-light bulbs and switch at the pedal have been replaced and all fuses an relays are fine. Could the two problems be linked? Automotive electrics are an enigma to me so any clues would be greatly appreciated.