I am the owner of a 1.4i citroen zx from 1995 (no aircon). Until recently it has never given much trouble. Now sometimes when I press the brake pedal the battery light comes on. This leads to ancillary power going off (like car battery, electric windows etc) but the car still drives ok - presumeably on battery power. The problem is "random" and sometimes occurs for a few minutes without having to press the brake pedal to provoke it. Driving on bumpy road sometimes seems to fix it though. Sometimes when the problem is ongoing I can hear a kind of electrical buzzing noise which seems to be coming from under the dashboard somewhere beneath the steering wheel. Haven't been able to pinpoint exactly or make the problem go away by shaking on the wiring. I suspect that the problem is due to an electrical short in the brake light or related circuit (when the problem is active taking out the fuse "fixes" it and puting the fuse back triggers it again). Maybe I need to fit a new brake light switch and see if the problem goes away. As the problem is random and never lasts more than a few minutes I am having trouble tracking it down. Maybe a faulty brake light switch which sometimes "shorts to ground"? Anyone any ideas on best way to proceed and what could be the problem...