Electric problem - fuse blowing

[defuzz]

The fuse keeps blowing for the rear left sidelight/brake light
(fuse A6 5amp fuse)

How do I diagnose what is causing it to blow? As soon as I turn on headlights, the fuse blows.

[ChrisW]

Take all the lamps out and try it, if it holds put them back in, one by one testing the circuit each time, hopefully it will 'pop' after putting a certain lamp back in - if it does take the lamp back out and check the condition of the connectors, earthing etc. to that lamp.

If it still pops with no lamps in at all its going to be a pita but you'll have to go over each lamp one by one checking connections  :roll:

[Range Rover Blues]

Mine was doing that.  It was the backlights on the radio that were doing it.  You'll need to check a lot of wiring but it might make it easier to unplug the rear section of the loom at the A post if you can.