this is normal for dipped beam to come on dim with the sidelights on mk2s, and lots of other cars too! although, have you fitted a hid or relayed lighting loom? if so this will incorrectly bring the dipped beam on full brightness. in this case its an easy fix, look in the engine bay near the driver side headlight. down on the chassis leg is a ceramic coil thing about the size of a packet of polos with a yellow wire out of each end./ follow the wiring back from that to a 2 pin plug and disconnect it. then bin the coil
this is the dim dip resistor, which isn't required by law or the mot. they are prone to the wires rubbing thru onto the chassis leg and shorting out, which then sets fire to the headlight loom as its not fused!
though once removed you better check the sidelights still work before putting it back in for the mot
