Brown Wire Modification 128?

Lowtechprime

Lowtechprime

Retro Grouch
Hey All!
I've searched though all the results for Brown Wire Mod but can't find anyone talking about a 128....
Has anyone done this to their 128? For some reason I'm having a brain lock on trying to extrapolate
the X-19 procedure to the 128...... My accessories all see about 10.5 volts and I'm sick of it...
 
It's basically the same idea as the X...or even a 124 spider. Read any posts on how to do it to an early X with the same style fuse box as your car and follow the same idea for your 128
 
Running an extra power wire to the hot side of the ignition switch (or to relays driven by the ignition switch) and another line to feed the always hot side of the fuse block would do the trick. Additionally (Or) adding relays to the wipers and lighting circuits could reduce the need to add more power to the ignition and the fuse block.
 
Hey All!
In better trying to understand the electrical woes of the 128 (and Fiats of this era in general) I started making a color diagram of the wiring. I was just focusing on the power distribution circuits but then I fell down the rabbit hole and just did the whole diagram... After 2 days in Photoshop, I share it here.... It's for a Rally, but the only real differences are in the headlight wiring...

edit: for some reason the site keeps reducing the resolution, making it impossible to see the wire and trace colors accurately.. If you want it, just contact me, and I'll send it directly to you..
128_Rally-WireColor.jpg
 
Last edited:
Lowtechprime said:
It's for a Rally, but the only real differences are in the headlight wiring...
Click to expand...

And the fog lights, front turn lamps, front corner lamps, sidemarker lights, main & auxiliary dashboard gauge units, quad tail/reverse lights & lack of USA emissions equipment wiring. All different than a USA model.

Lowtechprime said:
edit: for some reason the site keeps reducing the resolution, making it impossible to see the wire and trace colors accurately.. If you want it, just contact me, and I'll send it directly to you..
Click to expand...

Load the image onto the Xweb server as an attachment instead of using a linked URL to an off-site photo host.
 
I did load it as an attachment... It was not a linked url or photo host... When I saved it back to my desktop from the site, it was reduced in resolution..... Does anyone have a U.S. market wiring diagram? Mine come from the Haynes Manual, which is England/Euro spec. There are so many relays and unplugged connectors on my car that don't appear on the diagrams I have... I can't figure out what they are for...
EngineBayRGT_Relay2.jpgEngineBayRGT_Relay1.jpgEngineBayLFT_Relay.jpgEngineBayLFT_Plugs1.jpgEngineBayRGT_Plug1.jpgEngineBayLFT_Relays2.jpg
 

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Lowtechprime said:
I started making a color diagram of the wiring. I was just focusing on the power distribution circuits but then I fell down the rabbit hole and just did the whole diagram... After 2 days in Photoshop, I share it here....
Click to expand...
Wow, that's much nicer than most of the workshop manuals offer (if they have any at all). Nice work, you should consider getting into publishing your own manuals. ;)
 
Lowtechprime said:
I did load it as an attachment... It was not a linked url or photo host... When I saved it back to my desktop from the site, it was reduced in resolution..... Does anyone have a U.S. market wiring diagram? Mine come from the Haynes Manual, which is England/Euro spec. There are so many relays and unplugged connectors on my car that don't appear on the diagrams I have... I can't figure out what they are for...
View attachment 32597View attachment 32598View attachment 32599View attachment 32600View attachment 32601View attachment 32602
Click to expand...
I have 128 wiring diagrams. Which year(s) do you request?
 
Haynes manuals usually have wiring diagrams for US spec cars too. Have you checked the library on Mirafiori.com?
 
The wiring diagram is at the back of the standard Fiat-issued, often year-specific Owner's Manual for your car.
 
Going by vague recollection of my 128's wiring...

Photo #1 is the emergency flasher (hazard lights) relay.
Photo #2 is the voltage regulator.
Photo #3 is the radiator fan relay.
Photo #4 is for emissions control equipment (pressure switches - removed).
Photo #5 is for the emissions control Weber electrovalve (removed).
Photo #6 is the fuel pump relay (left) & fuel pump relay starting switch (right).
Photo #7 is ??? (likely for seat belt buzzer, remove key buzzer, etc.)
 
Hey Jeff! Thanks! You think #6 is fuel pump? This car had a manual fuel pump when I got it, not electric... That's actually what started this whole thing, I'm trying to add an electric fuel pump....
 
Yes, a USA '73 128 originally came with an electric fuel pump as standard, mounted under the center rear of the car. Both my '72 & '74 have this, as well as the 128's I've owned in the past. They're factory wired for it & have the brackets/fittings there for it, even came with a metal shield to protect the pump. My original pump was an OE BCD rotary, now replaced with a Facet cube that's been running 20+ years (on my '72).

watermark.axd
 
By luck, I also need to update my 74 128, and one of the relays is funky. 6 months or so ago Carl basically suggested the same simpler situation, but I couldn't find his posts.
I think the way to go is using modern relays, fewer of them, and the Brown Wire changes.

I am trying to give the biggest pictures. It's also a good idea to use "vector" files rather than "bitmap" (JPG). I use CorelDRAW , SketchUp, and there are other which will help with vector. I'll get some more info too.
 
I'm adding this cuz might be a better format:

2020 128_Rally-Wire-Color.jpg


And I see that Xweb couldn't do vector. This idea:
Vector
===
It would be nice to have a color picture (great job by the way) with the wire colors stated to add too.
 
I am almost done with a more elaborate color 74 diagram, that I got off Mirafiore.... It shows something called an 'Interlock System Control Unit'? I don't think my '73 has that though.......
 
It may not. My 74 wagon does, as did my former 74 SL Coupe. It's a funny security device if I recall. Never worried too much since I don't lock my cars.
 
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