My 740's brake lights are on all the time when the headlights or parking lights are on, while they work properly when lights are switched off. In addition, the bulb failure lamp indicates bulb failure all the time, though all bulbs are ok. Sometimes the headlights (and so on the breaklights!) don't go off when ignition lock is switched off. I changed the "bulb failure relay" but it didn't help. Could the failure be in ignition lock? Any other ideas? Is the ignition lock difficult to fix?