Headlamp eletrical gremlins-please help!

[Tuckahoe911t]

Hello Folks,

The headlights in my '70 911T won't come on. Running lights and dash lights come on but no headlights. I have checked everything, and all wires and bulbs seem to be good. I pulled the relay and checked for power in the wires leading to it. Wires leading to prongs #86 and #30 have power when the light switch is pulled to the first position, when pulled to the second position they have no power. None of the other wires have power at either position.

This all started the same time my ignition switch broke, which I have replaced. Since then I have not been able to get the headlights to work. Any help would be much appreciated, as electrical work is most certainly not my forte. Thanks.

[TerryH]

Hello and Welcome!

Headlight switch, maybe?

Sorry, I can't be of much help, but let me bump this to the top. Hate to see a new poster ignored. Sometimes the posts come so fast here, questions can get sent to page 3 pretty quick.

[304065]

OK, let's fix your problem.

First, before you do anything else, go to the pelican main page, go to electrical diagrams, click on the wiring diagram for the '71 and save it. This is critical to understanding what is happening, and you have to use it to fix any early car electrical stuff. Most mechanics wouldn't have the faintest clue, so taking it to a professional is not an option. To help you with this problem, I actually have my '71 wiring diagram printed in color 11x17".

Ok, simple stuff first. Have you checked the fuses? Lower fusebox, fuses #3 and #4 should be intact- the little silver thing should not be burned through. Get your voltmeter, and check for +12v on the "battery" side of the fuses when the headlight switch is in the SECOND detent.

The condition you are describing is NORMAL for a '70- at first click, you get the parking lamps and the green telltale on the speedo, and power to relay 50 terminal #86 (which energizes the coil, but has NOTHING to do with the headlamps coming on- the relay is a changeover relay for the high-beam flashing), then when you pull to the SECOND detent, power to #86 is killed. At the SECOND detent you should see +12v on pin #87 of the relay.

My guess is that when you changed the ignition switch you didn't get the wires back on the correct terminals. However, the wiring diagram lays out exactly what color wire goes to what terminal, that should be easy to check/verify.

Good luck! The diagram is intimidating at first, but once you get used to it, you realize how easy electrical stuff is.

Now, anyone want to explain the flasher circuit for a SWB '66 to me?

[michigan]

Just as a side note, in my 77 911s, I have to have the ignition key in the start position to turn on the lights. Check that aspect. Also, be sure you are making good connections with your fuse. I had the high beams come on but, the low beam would not work once because of poor connections with the fuse. Go figure.

[ruf-porsche]

Engine has to be running for the light to come on.