Multiple electrical problems: Where do I start?

[Animal]

Hello everyone,

I have a 86 Spider Veloce. Besides several electrical gremlins, it's in fine shape. Since I have several electrical problems, I hope they all might be related. All these problems didn't exist at one point, but since I don't drive it too often, I can't say when they started to malfunction.

Problem 1: The general lights in the instrument panel do not light up. The individual lights for the oil, heaters, fog lights, engine, hazard, etc work fine. The ones that light up the general panel (e.g. speedo and tach) do not work. I pulled out the instrument panel and checked all the bulbs, and none are burned out.

Problem 2: Intermittent wipers not working intermittently. The regular and fast speeds still work.

Problem 3: Power mirrors do not work. When I first got the car I replaced the controller and it worked fine.

Problem 4: Cigarette lighter doesn't work. When I first got the car I replaced the lighter and it worked fine.


Where should I start the investigation? If the problems don't seem to be related, what should I do to solve problem #1?

Thanks,
Animal

[geh458]

Animal, I'm not going to be much help since my Alfa is a racecar, and the electrical stuff is pretty simple. For your problems however, there are all sorts of links to wiring diagrams within this forum. I'm sure you will be able to find what your looking for. But for now, I'd check the fuses first. I'm sure someone else will provide much more detailed help, so good luck.

[papajam]

Welcome, Animal!!

Gifford has it right. First thing is to check is the fuses.

Problem 1. Fuse #10 is for the dash lights (as well as the right rear and left front parking lights). If the fuse and it's contacts are OK, the rheostat is the next likely suspect.

Problem 2. Since the wipers work, that rules out fuse #6 which powers the wipers. The intermittent wiper control unit, also powered by fuse #6, could be the problem

Problem 3. The power mirrors are fed from fuse #4.

Problem 4. Fuse #7 powers the lighter.

[Animal]

Thanks for the tips so far. I checked the fuses. They are okay.

I asked a mechanic to check the rheostat (I assume it is the rotary dial which regulates how bright the lights get in the instrument panel), and current seems to be running through it. Weird thing is that the voltage doesn't seem to vary when you turn the dial. Since electricity is running through it, that shouldn't be the problem, or should it?

What else should I check?

[papajam]

Yes, the rheostat is the rotary dial. The wiring diagram shows 4 wires and 3 terminals on the rheostat; two yellow wires (input) go to one terminal - one from fuse #10 and the other to the clock. The black wire goes to ground. The white/black stripe output wire goes to the lighter light, rear defog switch light and most important, to terminal D6 at the dashboard connector to power the 7 dashlights. Try jumping the yellow and white/black wires at the rheostat. If the lights work, the rheostat or rheostat ground are NG. If the lights still don't work, the problem could be the D6 connector, broken foil on the dash circuit board, 7 burned out bulbs or the dash isn't properly grounded thru dash connector D4 (black wire).

[Roadtrip]

Check grounds, too.