my drivers side tail/sidemarker/running light fuse blew out, i think its #23, a few months ago and I had my mechanic replace it since my car was going to be there for new turbos anyway. A few nights ago it blew out again. I open it up and the mechanic had put a 20 amp in when it usually takes 5. I bought a pack of 5, put it in, and it blew as soon as the lights came on. I tried this again with 10, 15, and 20 with the same result. Now, driving home from work mypassenger side, NOT drivers side rear brake light blew out. Any ideas what would be causing this or how to diagnose? I have a b5 s4

 

The wires to the rear lights are shorting to ground. Check with an ohm meter.

 

what would i need to take apart to fix this? where is the ground?

 

The insulation on the wires might be cut, causing a short. This can occur anywhere
from the fuse to the lights.

 

Make sure there is no moisture in there.

 

Yep you are probably suffering from a short... Do not put higer amp in than specificated it could damage the wireing and posably causing a fire. ( Thats what hapened to my friend)

 

moisture in where exactly? The fuse box or the light assembly. I haven't touched the lights, thats the weird thing. Does anyone know where I should start to investigate?

 

In the light assembly. You have to remove it anyway to check for shorts.