Ignition lights comes on with sidelights?!

when the sidelights are on my mk1 golf gti 1.8cc the ignition light comes on , on the dash….   If I start the car the ignition light still comes on but the sidelights get brighter, now dare not use it incase there is a wiring fault… any ideas guys?

sounds like poor earths, check all the wires to the side of the head, battery -ve and the earth claw(s) above the fusebox