headlight problem

[ReadieeVTS]

Hi guys, got a problem with my headlights, the main beam doesnt work! As soon as i turn the light switch onto sidelights or dipped beam the full beam icon is illuminated, as soon as the light switch is off the full beam icon doesnt show. They dont work at all, ive changed the stalk and relay, have also checked the fuses and theres no fault there... what could it be?!!!

Cheers lee

[itavaltalainen]

whåt car dude?

[ReadieeVTS]

Mk4 1.8t... sorry bro forgot to state

[itavaltalainen]

use a multimeter and check the wiring, also to headlight loom. could also be GND fault, check GND for the headlights....

the lights share common ground. if this is not present you can end up with voltage on the other lines... i.e. put 12 on the sidelight bulbs, which compared to the bulb in your dash has a low resistance, so most of the voltage will go to bulb in dash... same thing for dipped beam or even full beam.

i can draw you a picture if you like (i mean an electric schematic where you see voltages if gnd is not present)

[ReadieeVTS]

If you don't mind mate? That went totally over my head lol got my mot this month so need to get this all sorted

[itavaltalainen]

here you go:

essentially rather than travel down the headlight loom earth the current looks for another path. and it finds it in the dash full beam bulb...