I have a ford focus ztec 2000 (Y). When dip beam is on al is fine but when i flick to full beam, all lights go out so not even low beam working. Any ideas? D

Check the low and hi beam relays might be stuck

Sounds like you may need a new valve cover gasket. This happens often in cars. GOOD LUCK FRIEND.

sounds like you replaced them because of this issue.that leaves the dimmer switch likely culprit

in the fuse board is the relay ,not sure what one offhand but the contacts could be burnt out in the realy ,hence the click noise but the lights not working

Highbeam Symbol problem
The high beam and low beam works the opposite for my Mitsubshi Montero 1998, when in low beam the high beam SYMBOL comes on and when i flick to highbeam, the symbol comes off

more than likely a fuse or a relay is bad. locate the fuse for the headlights (owners manual) and check if it is bad, if the fuse is good, find the relay and give it a flick or two and try the headlights then, if they work, its time for a new relay

Check for bad ground for low beam and bulb.

Also, check that the high beam works independently of the low beam for that mode.

check all battery leads and earth straps
"" car body and engen bay straps""
also check battery terminals are tight check its full of battery water too if its been low for a time bump it!
and have a ""drop meeter test"" done on the battery if its a bad battery it should show that up first time it could have cracked plates inside the battery its self, test by turning on head lights then hit starter, if every thing go's dead!!!! put ""good jump start"" battery on to car and try it again,,, all should work just fine then,,,,it could just be a flat battery?????

You need to replace the high/low beam switch

The main/high beam relay/switch must be stuck on high presuming the high beam stalk selector does not operate. Probably needs replacement.