White with black tracer wire question

[FredWinterburn]

I have at least 3 white with black tracer wires burnt up on our 71 124 Spider. At some time in history high current made a mess of them and likely due to a previous owner adding at least two other circuits to these shared grounds (and then a short circuit). Am I correct that generally white with black tracer wires are ground wires on these cars? Are there any exceptions to that colour code designation? These are melted pretty badly and are on two connectors. I found one ground connection under the nut that holds the flasher unit. Are most of the grounds ganged together and only connected to chassis ground at a couple of places? Are ground wires under the hood routed back into the cab to be grounded there? This in not the way I would wire a car but it's what I have to work with Fred

[18Fiatsandcounting]

I used to think there was some method to the wiring madness that is Fiat, but I gave up. In general, white/black and black wires are grounds, either permanent or switched (like the horn button or the door jamb courtesy light switch). However, black wires are used for positive leads from the alternator and the starter solenoid post. Admittedly those latter ones are larger.

Most of the white/black ground wires are behind the instrument panel and dash, but there are a few up on the driver's side of the engine compartment. Where are your burned wires?

I know I'm going to miss something, but here are the grounds that I recall for the early cars. There actually aren't that many:

Body to bellhousing (the main ground for the starter motor)
Battery negative to body
On the forward post of the voltage regulator mount, there are several black wires that are grounds.
The windshield wiper motor is grounded at the outer mounting strap for the coolant overflow tank.
The compressor for the air horns is grounded at one of the mounting studs.
The turn signal mounting bracket stud is also a ground for several things inside the cab.
All the outer lights (headlights, turn signals, parking lights, taillights) are grounded near to where they are mounted. Due to being exposed to more "weather", these ground often get crusty and go bad.

-Bryan

[FredWinterburn]

Bryan, Once again very helpful. The burnt ground wires are inside the car and at least one was grounded to the steering column mount along with a fat black wire (unburnt), which is the only ground connection I could find in there. That matches your memory. Some of the burnt ground wires I thought exited through the firewall but I might be mistaken. More work to do.....Fred

[18Fiatsandcounting]

I did some more checking of my notes. On that bracket stud for the turn signal flasher, there should be three ground wires: A large black wire which is the ground for the cigarette lighter, a smaller white/black wire which is the ground for the courtesy light (when the doors are both closed so you can still turn on the light with the switch), and another smaller white/black wire which is a ground wire to the wiper stalk switch. The wipers on the early spiders had an interesting feature in that when you turned off the stalk switch, the motor electric field would be grounded thus stopping the motor in its tracks, so to speak. That second white/black wire is the ground for that.

So my guess is that either the wiper stalk switch or the courtesy light got goofed up and fried your wires. It's pretty common for people to mix up the wires behind the center console, especially when installing a radio, so you might need to check all of those (cigarette lighter, emergency flasher switch, courtesy light).

-Bryan

[FredWinterburn]

Thanks again Bryan. The wire that was burnt the worst and must also have some other ground wires ganged into it, was the wire for the wipers. I confirmed this with the battery disconnected and the meter between it and ground. But it also is the ground for at least two other electrical systems, all on one 16 gauge wire! The courtesy light switch ground I will have to hunt down tomorrow (thank-you). I ripped out the aftermarket sound system immediately and the horrors within are now on a bench, never to return to the car. I may fuse the cigarette lighter while I'm at it with a 20 amp ATO fuse in the power supply lead. I added 2-1/2 feet of wire to the brake light switch wires and rerouted them over the steering column and away from the pedal box and clutch cable. Those two wires are in their own sheath now so I can't confuse them with anything else. Fiat was ahead of their time with cramming multitudes of wiring into a small space. My old Volvo and Morgan are from an earlier era where ground wires are separated from the live wires and more space is taken up for the overall harness. And the dashboards aren't made out of cardboard Regardless, it's a nice little car and will be a good driver once I get the wiring cleaned up! I was hoping to have this done so my daughter and her husband could drive it when they come to visit from Virginia, but I doubt it will be ready by then. Wiring is so much harder than mechanical things, especially when it's crammed in like compressed spaghetti. Fred

[18Fiatsandcounting]

Where in Virginia are your daughter and her husband? I grew up in the Shenandoah Valley, in the western part of the state.

Your questions prompted me to take a look again at my own wiring. Here, for the very first time and free of charge, are the grounds as I see them in my '69 and '71 spiders:
• On the forward mounting post for the voltage regulator, there is a black wire to provide the ground for the left side marker (parking) light as well as the left front turn signal/parking light assembly. In later cars, this location also provided the ground for the electric cooling fan. Also at this ground location is a white/black wire to provide the ground for the battery charge indicator relay.
• On the stud for the bracket for the turn signal flasher, there is a large black wire that is the ground for the cigarette lighter, one white/black wire to the courtesy light (the ground for when the door jamb switches are not grounded), and another white/black wire that provides the ground circuit for the windshield wiper stalk switch.
• A black wire to the left front heater box attachment bolt provides the ground for the heater fan motor.
• On the outer mounting stud for the coolant overflow tank, there are two black wires. One wire is the ground for the windshield wiper motor, and the other is the ground for the right side marker (parking) light as well as the right front turn signal/parking light assembly.
• The ground for the air horn compressor is a black wire to one of the mounting studs for the compressor.
• Outer lighting grounds for headlights and taillights are generally one of the mounting hardware bolts/nuts/studs. The front side marker and turn signal assemblies are grounded as noted in the bullet above.

-Bryan

[FredWinterburn]

Thanks again Bryan. Last week I did find the ground wire for the heater fan disconnected. Not being sure where it should go it just happens I mounted it to a left side heater mounting stud under a jam nut. Then I found another disconnected wire near the gear shift lever for the fan high speed circuit and a very dirty heater fan switch. Once cleaned and lubed it works again and the fan is quiet with no ugly bearing noises. I remember the Lada fans had poor bearings and would get noisy very quickly even if lubed. I pulled the decker panel a few days ago to inspect underneath and lube the joints for the windshield wiper mechanism, and this car has the motor grounded under the panel, likely not original but functional. Today I'll look for the extra ground wire under the dash. Then, hopefully next week I will have a go at the malfunctioning headlight circuit. I also still need to mount two relays to take the load off the weak Lada Ignition switch that will be going in. Although, in 11 years of Lada ownership I never had trouble with the ignition switch and these parts are exactly the same. However having seen how poor the switch contacts look, 75 amp relays will be going into the Fiat. Fred

[FredWinterburn]

Bryan, Forgot to mention that my daughter lives in Aldie, Louden County VA. Busy area and not where I would live as it's too built up, and getting even more crowded. Too close to DC I suppose. Made some progress today. PO had been using speaker wire for electrical runs here and there taped into other connections, and even a chunk of coax for a power cable to some unknown load long removed. Also found some crimp connectors not crimped with the wire just shoved into the barrel and taped (I always crimp and then solder). I repaired the corroded right hand map light slide switch and soldered new wires to it for all three wires (switched ground, ground, and hot). The middle map light switch had also been bypassed on the switched ground side. Not many of the mods make sense. The wiring won't be completely original, but it will be a lot closer than it was. Depending on what I find with the headlight high/low beam switch and whether I can adapt a Lada switch to fit the spot will also cause a deviation from standard. Chances are poor that the Lada switch will work but if it does, they are a dime a dozen. That will be the topic of another thread if it works out. The switch on it currently is nearly worn out and will still be a nearly worn out switch even if I repair the high/low beam portion. Fred

[18Fiatsandcounting]

I haven't been to Aldie, but I've flow into Dulles Airport more times than I can count. Yes, that whole area is growing rapidly, different each time I go back there once or twice per year.

Fixing electrical "gifts" left by the PO is one of my least favorite repair jobs. I almost don't do them anymore. But, it sounds like you are making progress.

-Bryan

[FredWinterburn]

I just realized that I repaired something I could have just torn out. The right hand map light is probably not original to the car, IE on the very right near the right hand door. Anyway, the car now has a functioning (still need to test) map light for the passenger footwell. I'm used to these on other cars, but I can't find a reference to one on this car. I should have bought a repro owner's manual. Probably will shortly! Fred

[18Fiatsandcounting]

The map and footwell lights were not original. The only interior light in the cabin (other than the gauge lights) was the courtesy light on the middle console.

-Bryan