Hi i recently purchased an 89 GTI 16v and noticed that one of the high beams was blown. upon examinging the bulb i found that it was fine. when operating the light switch i can have both side lights and low beams on both driver and pasanger side. when i put on high beams i have side light, low beam and high beam on drivers side. while only having side light on passenger side. i have taken a multi meter to test the volts and there is no incoming voltage at anypoint to the high beam light on the psenger side. therefore it cant be an earthing issue. i have no idea why putting on my high beams would make only one low beam turn off. i have checked all the fuses and they are all healthy if anyone has any suggestions they would be most appreciated thanks in advance chris
Try swapping left headlight bulb to right side and see if it works, just to rule out the dual filament bulbs.
have a look at your relay sockets, see fi there are any looped wires or metal jumper bars fitted. there was a mod that used to kick about back in the day where you would jump pins on the fusebox socket to bring both the dip and main beams on together (like when you hold the stalk back to flash people) when on normal full beam setting for maximus brightness. its not a great idea as it can overheat the h4 bulbs, this may explain why the dip is operational on 1 side when main beam is active. for the main beam problem, if the dipped beam setting works that side this tells you the earth for the bulb is fine the issue is with the white main beam power wire. i would trace this back as best you can looking for damage, and check over the lighting loom all over where you can see for wiring tape this is a warning sign for bodgery 9 times out of 10
