Windshield wiper wiring 1974 Spider

[Yadkin]

With that minor adjustment this schematic works with all five devices.

[18Fiatsandcounting]

Here is my custom dash showing the two wiper switches. As you can see that are both for the wiper controls.

Good to hear that you got it working, and the pictures helped me understand. That knob on the left on your dash was originally the stock control for the gauge lighting intensity, but if you've wired it up for a wiper delay, that's great.

See: https://www.midwest-bayless.com/Fiat-12 ... 50-u8.aspx

-Bryan

[Yadkin]

Here is my custom dash showing the two wiper switches. As you can see that are both for the wiper controls.

Good to hear that you got it working, and the pictures helped me understand. That knob on the left on your dash was originally the stock control for the gauge lighting intensity, but if you've wired it up for a wiper delay, that's great.

See: https://www.midwest-bayless.com/Fiat-12 ... 50-u8.aspx

-Bryan

Wow, I thought the dash intensity was a second potentiometer that I have hanging around for this project. Confusing symbol.

[18Fiatsandcounting]

Wow, I thought the dash intensity was a second potentiometer that I have hanging around for this project. Confusing symbol.

It IS confusing. To add to that confusion, some model years had a separate thumbwheel that controlled the intensity of the ideogram symbols around the heater/ventilation levers by the handbrake. And maybe also the orange ring light around the cigarette lighter. The lighting rheostat knob was just for the gauge lights. Dim, dimmer, and off.

-Bryan

[spider2081]

Here is my custom dash showing the two wiper switches. As you can see that are both for the wiper controls.

very interesting.
My 1981Spider and my sons 1980 Spider and 2 Spare rheostats that I have in my spare parts all have the same symbol on the dial as the control to the left in your photo. In the cars we own they are original and control the dash cluster lights I see where one would consider it related to wiper control and not a light control because the symbol does look like a wiper blade.
These units are internally fused. Looking at the back of the unit there are 2 terminals that appear cut off at the surface of the bakelite base. inside the control there is a thin wire spot welded to these terminal. If the dash lite circuit shorts the fuse blows so the resistor wire does not overheat. I think the fuse value is around 4-5 amps because of the wire size used in the circuit. I have replaced the internal fuse with a 3 amp inline fuse and it seems to work.

I think the white/black wire from the steering column switch is used in the park operation of the wipers. When the column switch is put in the "off" position the white/black wire switches to the "park" switch in the wiper motor assembly. The "park" switch then switched the ground to the Speed switch onto the motor brush. This grounds the motor armature winding causing its magnetic field to collapse and act as a brake to the motors movement the instant the motors "park: switch is activated. Raising the white/black wire above ground might allow the motor to pass through park and not stop at proper position. I would think this is more a possibility when the alternator is putting out then when it operates on battery voltage.
A friend stopped by today that use to have a 1975 Spider. He was pretty sure his car had a rheostat for wiper speed. So I don't know what years did or didn't.
Bottom line you have it working to your satisfaction, That is what counts.

[18Fiatsandcounting]

A friend stopped by today that use to have a 1975 Spider. He was pretty sure his car had a rheostat for wiper speed. So I don't know what years did or didn't.

Not to question your friend, but I thought the change was made a bit earlier, like cars up to 1973 had a wiper speed rheostat and cars 1974 and later used the two position switch. The knob looked the same so it's hard to tell from just looking. I guess it would really depend on when Fiat made the change to a permanent magnet wiper motor.

That white/black grounding wire is very important. It ultimately is tied to ground at the metal clip on the pedal box that holds the turn signal flasher unit. Make sure that wire is solidly grounded as it's the ground source for a number of dashboard items, and a bad connection can lead to all sorts of weird electrical gremlins.

-Bryan

[Yadkin]

Dim, dimmer, and off.

-Bryan

I installed these to take care of that problem: https://www.amazon.com/dp/B06XCK3CGJ?

And with the dimmer switch that I'm using (4-12 volts), they are dimmable.