Strange electrical fault on my Focus

[bishbash]

This evening I was heading down the motorway when all of a sudden everything electrical cut out, the dash died completely all dials/guages set to zero, odometer blank, raido looked like it was still on but no music. The lights stayed on but dimmed quickly. For some reason the airbag light and the traction control lights came on. The engine continued to work until I managed to get off the motorway then I stalled and couldn't restart.

So I called the RAC who came out, jump started it and couldn't find any faults. He checked the battery wasn't discharging, all ok. So we both scratched our heads and I went on my way. Car was fine for about 50 miles and 2 restarts (fuel/pies). Then when I was finally about 500 yards from my front door the same thing happened. So now I have a dead car sat outside, can't be arsed to do anything now, but will have to try jump starting it in the morning, in the hope that I can get to work and get it booked into a garage.

Any ideas what could be wrong?

ETA - It's a 52 Focus ST170.

Edited by bishbash on Wednesday 29th October 19:51

[Zad]

Did the engine continue to deliver power? Sounds to me like maybe the feed to the engine management dropped out, which in turn turned off the lights/instruments etc. Presumably the ABS module has it's own feed, but detected a system failure so illuminated the warning light. First thing to check would be the ACU fuses and relays, inspect them for water and any signs of a bad connection / arcing. I think on the Focus, they have their own "chassis management system" so if it continued to deliver power, I would look at the relays/fuses around that.

[focusboy]

ive had same sort of problem and it was a earth lead from the battery to the top of the nearside wing, have a look,

[bishbash]

Thanks for the info chaps, Managed to get it started but it went again on the way to work, this time the AA man swore blind that it was the alternator, as it wasn't charging the battery. So it's in the garage now having a new alternator fitted. I'm not convinced myself and think I may end up paying for something I don't f**king need.

[Apache]

the airbag light comes on when it loses 12v, if the alternator had packed in you would have a warning light and a steady loss of voltage not a sudden loss of power. I've heard of symtoms like these caused by a broken earth strap to the block but this would kill the engine as well I think. Perhaps a dodgy ignition switch?

[focusboy]

how did you get on with it bishbash?

garry