Left Turn Signal Doesn't work when Headlights are on
 

Just replaced the bulb for the left turn signal below the headlight on my 87 Targa. During that time, I also took both headlights to just clean behind them. Now, when I have the headlights on - the left turn signal does NOT work and the indicator light on the Tach stays ON. The right side continues to work inside and out as it should. When the headlights are off, the left side indicator light on the tach will go off, and all signals work as they should.

Got to be the new bulb or something there but nothing looks out of sorts.

Any ideas from anyone?

TIA

Sounds like it's backfeeding through the parking light bulb. Verify that the bulb is in and twisted all the way. Could also be that a ground got jarred loose.

Thanks. Gave that a try before - but didn't seem to work. I am going to buy another bulb and see if that is the cause.

Just to provide documentation for any future searches, the issue was I had the incorrect bulb in the light fixture. A double filament bulb is required so it works one for lights when on and then again when use the turn signal. Took me a bit to figure it out by researching parts, but luckily I did.