Hey all, i am having some problems with my electrical system in my 86 alfa spider. my turn signals never worked... anywhere on the car. one headlight lights up but not the other, bulbs are both good. and a few gauges are out. as for the turn signals, i broke the original switch and replaced it. they never worked prior to that anyway, but the wipers do work. i know nothing about wiring and some tips would be great!
When you say one headlight, do you mean high beam and low beam work on one side and not the other?
Others have passed along good knowledge. I'd add that the advantage of using an ohm meter is that they usually allow you to measure voltage as well.
After you've checked the fuses, and done some of the troubleshooting in the other posts..
Go to the headlight that's not working, unplug the connector, turn on the power to the light, and use the volt meter to see if you've got voltage at the light. If you've got voltage, then the problem is in the light. If not, then you can work your way backwards.
A wiring diagram really helps. Electrical problems, especially with the lighting, is usually pretty simple, you just follow the wires and check for voltage along the way. When you lose it, the problem is in between where you just checked and the last place you had voltage.
As for the directionals, same process. Check the obvious, the fuses, the flasher unit, and the grounds, then get out your wiring diagram and voltmeter and check for voltage.
Bad grounds are a common problem in these cars, even if they look good don't hesitate to disconnect them and clean them up.
HTH,
bs