Brake Light Fuse

I am currently having to change my brake light fuse every couple of weeks. although cheep and easy to do, this isnt exactly ideal. does anyone have any thoughts as to what might be causing this problem? i assume its a short of some sort but no real idea where to start. has anyone had a similar issue?
its an '86 90 with a 200tdi conversion

I'd start at the rear checking the light fitting bulb holders and connectors themselves

If not there, could be chaffed wire where wiring enters chassis

Also have a 1986 and had the same problem, I tried calculating the current on the lights alone thinking that the current on the fuse was less but didn't find the problem, the previous owner made some modifications. Anyhow, just stuck in a 30A in stead of a 20A. Bad advise but it worked for me.

The bulb holder might be full of water when it rains.

I had a couple of lights like that when I first got my fender. About £25 on ebay got a set of the 8 little round lights. Didn't have any problems once they were changed.

I would go with bulb holders 1st, they caused me a load of hassle. Easy to cheap, easy fix and cheap to replace.

G

just had a similar problem,turned out to be chaffed wire to reverse light switch,brake lights and rev lights share same fuse on mine 1998 model,dont know if same on yours,i know theres a lot less guses on early ones so perhaps the fault lies elsewhere