Problem with Drivers side headlight

[wytlytning]

The drivers side headlight on my '00 GT is dull. The pass. side is fine.
When I hit the brights nothing happens to the dull drivers headlight at all.
If I flash the brights, it goes out completely. Has this happened to anyone? I hope it is just a bulb.
Thanks

 

[n0v8or]

It sounds like you have lost the ground connection to either the bulb or socket. It could be broken within the bulb, but, unfortunately, that would be very unusual.
The light is dim beacause, with the low beam powered, the current returns through the high beam filament (it has no other parh without the ground), so the two filaments are operating in series.

The usual wire colors are:
Lo beam filament - white with green stripe
Hi beam filament - green with black stripe
Ground - black

 

[boomshack]

That happened to me as well. Could be that the housing around the bulb's base needs to be tightened as they tend to get loose on 99-04 mustangs. My mechanic fixed it for me for free and took less than 10 minutes.