Turn Signals don't work when Headlights are on

[Doakster]

Weird issue has come up for me, my turn signals no longer with with the headlights on, with the headlights off they work fine.

I had been installing some gauges recently but didn't wire anything off the headlight/turn signals.

Any thoughts?

[rabbitman]

Bad grounds seem to mess weird stuff up.

[Vincent Waldon]

Grounds grounds grounds grounds grounds.

Did I mention grounds?!!! 

The running lights (which come on when you turn on the headlights) and turn signals are the same bulb with two filaments and a common ground.  If that ground lifts very funny things happen.

I'd be inclined to pull all 4 turnsignal/running light lenses and bulbs and clean everything up with fine sandpaper... looking for broken brown (ground) wires while you're at it.

[Doakster]

Grounds grounds grounds grounds grounds.

Did I mention grounds?!!! 

The running lights (which come on when you turn on the headlights) and turn signals are the same bulb with two filaments and a common ground.  If that ground lifts very funny things happen.

I'd be inclined to pull all 4 turnsignal/running light lenses and bulbs and clean everything up with fine sandpaper... looking for broken brown (ground) wires while you're at it.

The weird thing is, i installed a set of E-Codes, and everything was working well. Car sat for a few weeks and i installed some gauges today and that's when the problem started.

I don't think it's the grounds at the turn signals themselves because the turn signals work perfectly fine without my head lights on, once the head lights are flipped on, the turn signals won't flash.

I'll have to go back and look through  my bentley to look for the grounds.

[Vincent Waldon]

When you turn on your headlights you are supplying power to the other side of the turn signal bulb aka the running lights.

If that socket is missing a ground and was using the running lights as a phantom ground the turn signals will now stop.

Headlights off: turn signals ground thru the running light filament and work fine.
Headlights on:  turn signals can no longer ground thru the running light filament and stop working.

The issue can be anywhere in the ground circuit... the brown wire that grounds the socket, corrosion between the wire and the socket, corrosion between the socket and the base of the bulb, and on rare occasions corrosion between the  base of the bulb and the internal filament.

All of this assumes the issue is unrelated to the recent wiring.

[Doakster]

That makes sense now. Are the grounds coming off the turn signal filaments going back the body some where? Or when does the ground go back and connect to?

[Vincent Waldon]

Each light fixture will have a brown wire as part of the harness... that be the ground wire.

[Doakster]

Found my problem, my own fault.

I had replace the turn signals with clear lenses, and bought new amber colored bulbs, i didn't pay attention to the fact that it has to be dual filament and bought single filament bulbs.

Time to go get the right bulbs.