Wt heck! Headlight works if left signal on!
 

Greaaat another impossible electrical question, this guy! It's so strange, no headlights unless left signal on! Huh??

1984 911. Electrical dummy here. I'm sorry!!

Mm. Thinking. Was it working before?


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No telling without extensive troubleshooting. I see on the early 911 diagram that the headlight switch and turn signal stalk share a conductor. Its possible that B+ at the headlight switch is faulty and the turn signal is back feeding the headlight. I’m really guessing.

When electrics start acting looney as in your case, the first thing I look for is a bad connection in that circuit, a bad ground primarily. A fairly complicated groupe of switches though, light, combo and hazard. Any number of possibilities. I would start by looking at the turn signal light bulbs to see if single and double contact bulbs are in their correct sockets. You will need a good wiring diagram with plug location info. Bob

I had the same issue. I replaced the stalk for high beam and turn signal as stated in post #3 and that fixed the problem. Part number 91161330501

Probably a problem with the switch mentioned above. If you take the cover off you may be able to tweak the contacts to get headlights working. Do brights work? I had an issue where headlights went out between brights and dims, a litte tweak and all good. Switch ordered.