Just now, SteveJ said:

Yes, because you are backfeeding the circuit.

Gotcha.  The only place where dual filament bulbs should be are the top outer lights of each 280z style housing, correct?  I remember that the only dual filament bulb in the whole car is plugged into the driver's side top outer bulb socket.

Incorrect. There are also dual filament bulbs in the front for the turn signal/marker lights.

17 hours ago, SteveJ said:

Incorrect. There are also dual filament bulbs in the front for the turn signal/marker lights.

Glad to say:  Euro version does not have that (crap).. haha.  the only dual filament bulbs are the running light/brakelight.  (and some people manage to push the bulb so hard into it's filament that the brakelight becomes the running light and viseversa..   watch carefully the side tabs on the bulb.. they differ in hight position on the fitting. When you push them in and turn it has to go easy.)

thanks for the info guys.  next time im at his place ill try these suggestions!

5 hours ago, dutchzcarguy said:

Glad to say:  Euro version does not have that (crap).. haha.  the only dual filament bulbs are the running light/brakelight.  (and some people manage to push the bulb so hard into it's filament that the brakelight becomes the running light and viseversa..   watch carefully the side tabs on the bulb.. they differ in hight position on the fitting. When you push them in and turn it has to go easy.)

Good point, sir. I forgot to bring that up. Yes, it is a challenge, but you can get the bulb in the socket wrong. As Egon said in the movie Ghostbusters, "Don't cross the streams."