At various times, I get different warning lights coming on, from bonnet open to engine malfunction, oil etc. Sometimes all together, sometimes singly and sometimes none at all. I just went over a bump in the road and they all came on together and then went off again shortly after. Looks like a loose connection somewhere, but where? Battery connections are tight and the passenger side fusebox seems connected ok. The local garage can't find anything. Any suggestions would be gratefully welcomed. Thanks guy.

Loose or corroded connection on one of the BCM connections (under the glovebox)

Did you check the earth from battery to body?

is this a mk2.5 focus?  There is the common focus mk2 problem with cracked solder on the pins for the connector to the instrument console. generally it is felt that it affects earlier cars but as time goes on i have seen it mentioned on later cars also. i think maybe it has just taken more years for it to become apparent on the later cars.

try banging the instrument console and see if that recreates the erratic behaviour of the warning lights. 

 

I hit mines regularly cos it creaks and clicks too much.

Thanks for the advice folks. I decided to follow the cracked solder idea and on removing the dash, I found the cluster connector was loose to the point of almost hanging off. I cleaned all the contacts with electrical cleaner, shoved it all back together and hey presto, problem solved.

someone must have put that back on wrongly in the past. the plug has that kind of level/clip thing on it. if put on properly I can't see how it can come loose. Lucky for you it was that easy to sort it.

Famous last words. Three weeks later and it goes again. I'm thinking cracked solder.