Hi All
Just high beams, ok, so replace fuses, and then take out the high beam relay ( either in the engine bay or under dash i cant remember )
Then turn of the high beams, if you loose the high beam, then the fault is between battery >> switch >> fuse >> relay BUT NOT relay to headlight
Use this as a process of elimination
If it is after the relay, then replace fuse again, and remove headlight socket and remove bulb or disconnect the small harness if fitted to head light, then turn on headlights again, if it blows then it is between relay and bulb socket , so that means its the wiring or connectors or the bulb socket itself ( wear / damage / rust / water leak
If it does not blow but blows when the bulb is in place then its the bulb or the socket
And you need to try and disconnect the other side to narrow down it is it left or right sides with issues
Unfortunately trial and error or process of elimination
regards
george
