johnehowe911

I was driving my 87 911 the other night and the headlights went out. The running lights were still working fine. I turned my fog lights on and continue home.

I have been troubleshooting the problem. When looking at the fuses I noticed that one of the low beam and one of the high beam fuses are no longer hooked up. While using a voltmeter I was able to determine that the ignition switch is suppling the needed 12 volts to the Headlight switch and then from there also passing through the dimmer switch. My electrical drawing shows that leaving the dimmer switch it goes through the fuses in the trunk and then to the head lamps. Since 2 of the 4 fuses for the headlights are no longer connected I suspect that the previous owner has installed a relay to switch the headlight to relieve the current from passing through the headlight and ignition switching. However I am having tremendous problems tracking the wiring from the dimmer to the suspected relay wherever it may be? I have even tried to trace from the headlamps backwards to no avail. Any ideas where they may have installed the relay or any additional tips on troubleshooting my problem?

steve911

(Usually), a new headlight relay set up is installed near the fuse block (I put mine right next to it). Doesn't sound like this is the case with yours. It might be that there is not a relay installed; I don't have a wiring diagram handy, but the fuses might be jumped together. You might try cleaning all the fuse contacts and replacing the headlight fuses with new ones, just to rule out the fuses. I've seen it where the fuse looks good, but doesn't work; replacing it made my problem go away (mine was a problem with the electric windows not working).

good luck; electrical gremlins are no fun

scottb

If no relays, your high beam/turn signal switch may have cooked. If so, add the relays and buy a new switch. The toughest part in replacing the switch is wiring it into the back of the headlight switch. Lots of wires, so do them one at a time, and go slow.

And, if memory serves me correctly, I only had one fuse for the low beams and one for the high beams on my 84 (for a total of two fuses).

sschmerg

I don't know if this is the case for you, but I will reiterate what Scottb wrote: Many, many times the headlights don't work because the turn signal/high beam switch has gone bad. I've replaced it on both 911s, and in both cases that was the culprit.

-Sean