Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

Today I managed to instal a head unit in the mess of wires that was behind the center consol. After trying different wire combinations I kept turning the ignition on to see if power was getting through to the head unit but i must have messed up something because now when the key is in the position that the ignition lights are lit they arent. The car still starts but the battery light is then on and the temperature gauge and the fuel guage arenot showing the correct readings. I think this happened when i connected the earth (thickish brown that i thought was a live) and a thin black (not sure what this now is for) wire to the unit.

Have i just blown a fuse or relay somewhere?
Or have i messed up the alternator?

Hope some-one can help

Now fixed. It was a fuse that had blown. had to check each one in the fuse box to find it though, one of those labled KE15 i think.