Well after a little fender bender last fall my driver's side turn signal light doesn't come on with the headlights. The green arrow inside the car stays lit but when I put the left turn signal on the lights inside and out flash no problems and work as normal. Any ideas why this is happening?

'86 GT 4spd if it's relevant

Broken bulb!

The flasher requires that all bulbs on that circuit be lit in order for the flasher to heat up enough to flash. If a bulb is not working it just generally does not flash or it flashes very slowly.

Usually a bad ground for me.

Bad ground. Same thing happened to me the other day. Make sure the metal strip inside the socket is in contact with the side of the bulb base.

Nolan

Ok I'll check the ground in the morning and I'd like to point out again that it flashes perfectly normal when activated. It's just when you turn the headlights on that the green arrow stays lit and the bulb stays off, but using the turn signals seems exactly as it should.

Burnt out filament on the running lamp (the not so bright filiment) side of the bulb, or somehow that portion of the bulb isn't making contact. Yep the dash light comes on when that part of the bulb burns out. That's the way it works.

The brigher filament, that is the turn signal filament, still is ok btw.

[This message has been edited by phonedawgz (edited 08-03-2010).]

^ what he said

When the dash light stays on, that means an open circuit to the bulb, which is usually a burned-out or broken filament. A sure way to tell is to swap the bulbs left to right. If the problem switches to the left turn signal, you know it's the bulb. If the symptom does not move to the other side, you have a wiring fault.

fyi - when the bright filament is burnt out - usualy the dash light comes on when you signal that way but it doesn't flash. Sometimes it flashes really slow. Also of course there is no turn signal light at the bumper.

so - dash light on when its not supposed to, or not flashing when it IS supposed to - check bulbs first.