Wiring Loom Review

Project Alfa Romeo Guilietta Spider
Excerpt from March Issue of European Car Magazine

Part Five: Automotive Neurology
by Dave Mericle

PHOTOS BY THE AUTHOR

Project Giulietta has come a long way in the last few months. Now that the Spider is once again covered in a good coat of paint, it is time to perform the next serious operation – rewiring the car.

Nervous Disorder
If you think of a car in physiological terms it might go something like this: The engine is the heart, the brake and fuel lines are the vascular system, the wheels and tires are the legs, and the electrical wiring is the nervous system. Looked at this way it turns out the Giulietta Spider was due for a nervous breakdown.

I originally pulled the wires from the car when first stripping it for painting. Under close examination the stock electrical harness of the old gal was fairly intact but severely degraded. Time had not been kind to the wiring, and it was really showing its age — a little explanation is in order here.

Back in the ’50s, Alfa Romeo was just beginning to learn the ropes of the mass manufacturer trade. While it had the chutzpah to design and build almost everything for the Giulietta series itself, certain key components were farmed out. Most obvious were the brakes (Girling) and the electrical system (Lucas). For better or worse, both systems were Brutish, er, British in origin. The net result of this Italian/British wedding of parts was a wonderful diminutive car featuring good power, excellent stopping characteristics and somewhat problematic electrical controls.

To be fair, some of the gremlins lurking in the circuits of the Giulietta series are due to the fact that Italians of the time seemed to think that paint over metal would complete an electrical circuit. And paint – no matter how beautiful the color or shape it clothes – just doesn’t make a good ground. An important fact to bear in mind is that 99 percent of all electrical problems on Italian cars from this era are due exclusively to bad grounds. The major components – switches, starters, generators, distributors and gauges – don’t actually fail with more frequency than those on other cars from other countries. In most cases they simply didn’t have good grounds and therefore burnt out.

Compounding this problem was the relative primitive plastic technology of the time. Bakelite, as it was then known, was expensive and seldom used. Certainly it wasn’t used in the wires forming the harness of the Giulietta series, which was usually composed of either copper or aluminum core wire, wrapped in asbestos paper, then bound up in cloth of various colors. While it worked for a time, this type of construction was prone to aging and would quickly become brittle and broken – contributing to more shorted-out circuits and components.

I found all this out firsthand the moment I tried to pull the old harness out of the car. Most of it simply cracked and fell apart in my hands. No matter how gentle I was with the wires, they kept parting with depressing regularity. Clearly it was time to replace the whole affair.

Live Wire
The next step was to search for a company – one familiar with early Giuliettas and all their quirks – to fabricate a replacement harness. After a time I found a company down in Texas called Auto Italia Sportiva (AIS) – a one man show owned and run by Lionel Velez, automotive wiring expert extraordinaire and a real “live wire.”

Velez is well versed in the arcane art of Italian automotive electrical system design, and is particularly knowledgeable about Alfa Romeos. After discussing the Spider’s wiring problem with him I decided to use one of his cloth reproduction harnesses to replace the old tattered one in the Giulietta. Each harness is hand made to order by Velez, allowing him to better handle custom requests. I waited about three weeks before the finished product arrived at my doorstep.

On close examination I found the AIS harness to be of superb design, appeal, quality of construction and workmanship. It features modern copper wire cores sheathed in PVC, then wrapped in cloth. Velez supplied high quality cloth-wrapped wires which marked the original color-coding –the replacement harness duplicated the old one shade for shade. He also took the time and trouble to make sure all the connectors were a proper match as well. (In case of the Spider, most of the ends were the original infamous bullet-type “Lucar” connectors.) 

Velez stocks good modern reproductions of the original ends and hand solders every one on the wire tips, instead of crimping them. To top it off he includes a blow-up of the original factory wiring diagram for the customer, then laminates it so dirty fingerprints rub right off!

Compared to modern cars Project Giulietta hails from a simpler time – before OBD-II and the bewildering array of power train monitoring devices, power windows and door locks, and various safety features such as airbags. While the new Spider harness looked fairly complex straight out of the box, it could have been far worse – by an order of magnitude – if the car had been made today.

Sorting Spaghetti
To begin putting the whole mass of wires – which resembled brightly colored spaghetti – into the Spider body I first laid everything out on the garage floor, and began noticing some of the major branches in the system. Then, using some spare labels and a pencil – and by referring to the laminated wiring diagram readily at hand – I began labeling every circuit I could. Within an hour I had identified what wires went to which components and had a pretty good idea of the overall orientation of the harness. Trust me – if you ever attempt this chore – label everything you can. It will save you lots of time, effort and confusion in the long run.

Basically, the Giulietta wiring harness is simple and breaks down to several major branches. All the separate wire bundles start at the fuse box up under the dash and branch out from there. From this central point inside the car they go through two electrical access holes in the firewall sheet metal, both of which are located high up on either side of the engine compartment.

On the passenger side of the engine bay there are three main bundles of wire. One carries the combined wiring for the passenger-side headlight, parking light, ignition coil and water temperature sending unit. Another bundle – easy to identify because it’s the longest section – provides power to the rear of the car and includes wires for the taillights, license-plate light and the fuel-level sender unit located in the gas tank. Finally, there are two low-gauge fat wires together in a bundle (which is the shortest of all) that go to the starter motor.

The driver-side engine bay wiring is made up of just a couple of bundles. One carries the circuits for the driver-side headlight, parking light, horns, horn relays and the voltage regulator. The other supplies current to the brake-light switch and the oil temperature-sending unit (located at the bottom back of the oil pan).

The center main bundle is the largest by far. The thickest branch with the most wires goes to the fuse box, located under the dash just to the left of the steering column bracket. Also on this side are bundles for the instrument gauges, ignition switch, and the headlight high beam floor-mounted dipswitch. Another set of wires branches out to the right side of the dash. These carry the wiper and heater motor circuits as well as the under dash switches.

Eye of the Needle
After identifying and labeling all the wires and branches of the new harness, it was time to install it in the Spider. This turned out to be a tight, close-quarter procedure. I’d compare it to trying to put several strands of thread through the eye of a needle – one after another. To begin with I laid several old blankets on the floor of the car in the driver and passenger foot wells – some padding was in order to lessen the pain inflicted by the cramped spaces.

Taking the entire harness in hand, I put the central section up under the dash of the car, draping the bundles for the fuse box and all of the driver-side engine compartment wires to the left of the steering column and everything else to the right. This left the harness pretty much evenly divided on either side up under the dash.

Then, beginning with the passenger side first, I began threading the bundles of wire separately through the engine bay access hole in the firewall. (At that point I was sitting cross-legged in the passenger footwell, hunkered down and peering up under the dash with the aid of a flashlight.) First to go through was the longest section for the taillights at the rear of the car, then passenger side headlight group and, finally, the starter motor wire bundle. Working the last bundle through was a fairly tight fit. This method of wire threading – starting with longest bundles first – worked fine. But any order would have done just as well, as long as everything fits through the access hole in the firewall.

After getting all the bundles of wire started, I went around to the engine bay and finished pulling them through almost as far as they would go, leaving some slack for final fitting. Once the passenger side was done, it was time to turn my attention to the driver-side bundles. The under -dash area on the driver side is even more cramped than the passenger side, due to the location of the steering column bracket. Using the same procedure as before, I carefully threaded the driver-side headlight and brake switch bundles up through the electrical access hole in the firewall. This procedure is further complicated by the fact the main structural support for the dash runs across the width of the car just under the windshield area, and the access hole is situated directly above it. Taken together – between the dash support, the steering column bracket and the extra wiring for the fuse box hanging in this area – it’s almost impossible to see the access hole directly. So I wound up threading the bundles by feel, and it was definitely touch and go during this part of the rewiring operation.

With the main bundles of the harness on both sides threaded through into the engine compartment, the remaining wires under the dash didn’t appear so confusing. It remained a simple matter to separate the various sections going to the fuse box, gauges, assorted switches and the windshield wiper and heater motors, and lay them in place. Attaching the wires to the final end -use parts will have to wait until later in the evolution of Project Giulietta, because all the electrical components were removed from the car for media stripping and painting.

Wrapping It Up
A few more chores remained, however, such as attaching the rear taillight harness bundle to the body. This portion of the wiring runs under the car on the passenger side of the center frame rails by the drive shaft, along with the fuel and brake lines, and is held in place by bendable sheet metal clips welded on at the factory. Thus it was a simple matter to get under the car and string the harness up in place after all the work under the dash and in the engine compartment was done.

The battery position in Giulietta Spiders is in the trunk on the passenger side, which follows time-proven sports car strategy. It shifts the center of gravity toward the middle of the car by partially compensating for the driver’s weight as well as helping to even out the nose-heavy weight distribution inherent in the Giuliettas’ classic front-engine/rear wheel-drive design. However, one of the compromises dictated by this setup is long battery cable length, which in the Spider approaches 12 ft. The inevitable result is a perfectly natural voltage drop from battery to starter because of the long span of the wire. Since the original battery cable was still with the car, and was in much the same shape as the old wiring harness, I decided to replace it. I opted for a modern copper-core 2-guage battery cable substitute for the old one, and installed it while hooking up the rear taillight harness bundle under the car.

To help seal the access holes in the firewall between the interior and the engine compartment, Alfa originally used rubber oval-shaped grommets covered by metal split-oval retainers. This arrangement secures the wires as well as keeps engine noise and fumes out of the car interior. Since I’m not far enough along with the new harness into various electrical accessories, fitting the grommets and retainers will be covered in a future installment of Project Giulietta.

Cost for this stage of the restoration ran $850 for the AIS wiring harness and $20 for the battery cable. All things considered, it was cheap insurance against future electrical problems (if not an outright fire, given the condition of the original harness), and replacement turned out to be the right thing to do at the right time. Now the Spider’s potential for a nervous breakdown somewhere down the road has been effectively avoided, which in the long run can only be seen as a good thing. Stay tuned.

**This article has been published with authors’ consent. **

Leave a Reply