Car starts and runs fine. Then as soon as i put the lights on or indicators it cuts out.

I thought it was the earth off the battery so i took it off, cleaned it and re earthed it but no joy.
Took the battery off my van which is a new one tried that but still the same.
Altenator is newish done probably a 1000 miles or so, so i doubt its that.

Could it be another earth somewhere? Was going to clean and re earth them all anyway just too be sure but its gone dark lol

What else could it be...?

Cars an xr3i efi