Two power feeds to Headlight switch?!?

[Amendonsa]

Hi Everyone.

First post, but have lurked here for a while. Finally diving into my 1973 Spider and have run into a few, shall we say interesting issues.

The first was no power to tail lights or side marker lights. With the help of the diagrams, traced the power to the headlight switch. Found some aftermarket, heavily taped 3 position switch. I have located the following, but am confused as to the last.

Black wire- 12v. Constant power, regardless of ignition switch.
Green wire- I can jumper this to black and headlights work fine.
Black/White wire- Jumper this and side and rear lights all work great.

Brown/Blue wire- This is two wires crimped into one connector. I was thinking this was to power dash lights or some accessory, but I found that this was also constant power, like the black one.

***EDIT*** I started looking at later wiring diagrams and believe I have been able to answer my own question. I think I was a little too focused on a '73 Spider using a '73 Spider wiring diagram. The later diagrams posted seem to match more of what I am looking at, and make WAY more sense!

[seabeelt]

One is for constant power to provide power to the side markers in the half way position ( parking lights position) and the other to provide power to the head lights. It is very confusing until you work out how the switch actually works and what circuit is supposed to be on when.
R/

[Amendonsa]

So confused!

It doesn't help that the PO used a three position, generic Radio Shack switch, hot-wired both the keyed and constant power wires together to a single terminal on the switch and taped everything together until it got hot, melted and brown!!

But, learning about all of this is great fun. I made the mistake, I'm sure the first of many, and assumed that the 1973 Spider wiring diagram applied to my 1973 Spider! Since I looked at the '78 things are making MUCH more sense.

Thank you very much for the reply. Great community I have stumbled in to!

[RRoller123]

Welcome aboard! You will find plenty of knowledgeable and friendly people here.

Here is a thread on how to post pictures directly to the forum:

http://www.fiatspider.com/f08/viewtopic.php?f=4&t=21014

And here is another picture-posting thread:

http://www.fiatspider.com/f08/viewtopic ... 12&t=23084

And here is a link to a map of Spider owner’s locations. Many forum members have listed their locations.

https://www.zeemaps.com/map?group=191825

Pete

[bradartigue]

Assumed that the 1973 Spider wiring diagram applied to my 1973 Spider! Since I looked at the '78 things are making MUCH more sense.

Late 73 is a 74 and a 74 is a 78, wiring wise. Sort of. It is a heck of a lot easier to figure out how the cars were wired by going by the body type (CS2, CS0, CS, BS, etc.) and the original engine as fitted to the car.

I would like for someone with a FIAT computer (Bruce from Bruce's had one but I don't know if it ever worked) to take a service code from the VIN plate and see what the hell comes up. I've often wondered if it would tell you what references to use, because the model year meant nothing to FIAT. Rolling assembly changes, not model year changes.

Get yourself a FIAT switch and the wiring harness from the headlight to its plug under the dash and save yourself some misery; at the very least make a new one with good wire and a stock switch. It isn't hard.

[Amendonsa]

Thanks Brad.

This is my first foray into electrical, and I cannot tell you what a huge help your diagrams have been. They have kept me from throwing my hands up in complete despair! Amazing amount of work you have put into those. I was way too focused on years as being important.

I have no idea what the body types mean yet. With the help of your guide I have identified that I have a 1592 engine, but haven't gone any deeper.

I have a Fiat switch enroute as we speak. Now on to the next wire bundle! I found that the hazard switch in the console was connected to nothing. Tucked under the dash was another hazard switch, completely wired and about 18 random wires that are cut and taped. Now to figure out where they go. This is fun!