Symptom/Solution: Front Turn Signal/Marker light only blinks when head lights are off
 

911SC (1983)

Symptom/Solution: Front Turn Signal/Marker light only blinks when head lights are off .

This might seam like a silly one, but it actually caught me and the parts counter guy at a Porsche dealership off guard. When replacing the marker light bulb(s) on my 911SC I discovered that the Turn signal/marker light would only turn on when the head lights and running lights were off. Turns out that I needed to remove the two retaining screws for the cover remove the bulb and rotate it ½ turn and reinsert.

Once this is done it will function properly.

The reason for this is that there are two elements in each bulb (one for the marker light and one for the blinker) If installed upside down the much brighter blinking light remains on static, as it thinks is a marker light and the much weaker filament (now blinking) is blotted out by the super bright filament. Don’t feel silly, it took me a few minutes to figure that one out and even worse I replaced both the bulbs upside down so it really threw me for a loop. The part counter guy was extremely helpful; he insisted that is was a wiring fault.


Side Note:
All I can say is Thank you, to everyone who has posted up trouble shooting tips to the group. It has already helped save my bacon a few dozen times. I’ve now managed to get enough experience under my belt to be dangerous and as my first trouble shooting post I figured I’d start out with something simple and a little self deprecating. LOL

I hope this helps someone.. Akira28


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1983 911SC
1984 944-NA

I hate to resurrect an ancient thread. But I had nearly the identical symptoms.

in essence - the only time the bulb would blink would be when the headlights were turned off. In this case my driver side front.

I pulled the cover to flip the bulb - realized while inspecting the bulb (while off the car), when shaking it made a metallic rattling noise - so bad bulb. I bought a pair of new bulbs. At least in my car ('82 SC), the clocking for the bulb only allows you to enter the bulb one way.

So I ultimately swapped both bulbs to put new bulbs in both front corners. Then I tested with headlight off. Now the blinker DOESN'T work with headlight off. With the headlights on and the DRL mode (half pull on the headlight toggle), the blinker works, but the flashing is a little less sharp than the fully functional side.

I'm guessing maybe a slowly dying relay or possibly just "car getting old" and the wiring is going. Will dig into it more. But if anyone else has ideas/guidance before I start really tearing in the wiring - would be much appreciated.

If you changed the bulbs in the front and the flashing changed, I'd check the sockets. I doubt if the relay is bad.