"The YnZ Harness"

There are approx. 60+ different variations of the 356 wiring diagrams from 56 through 1965 all models included. As you often hear, shopping around can be a good idea. When it comes to 356 wiring harneses, there really isn't one that is better than the ones produced by YnZ's Yesterdays Parts.

What makes the YnZ harness so special? First of all, each harness is replicated from an "orginal" harness! If you order a harness for a 1958 A Cabriolet, the happy employee assigned to building your harness, runs upstairs to get an orginal 58 A Cab harness. Upstairs there are racks full of boxes containing original harnesses for a wide variety cars, and yes, the 356 Porsche has its own rack.

The original harness is anchored down on a very long table and the new harness is built right over the top of the orignial. All wire sizes, colors and terminal ends are exact to the original factory specs. Its is a very time consuming process, but well worth the wait.

Another great assest of YnZ, besides the beautiful harnesses, is the history and intimate knowledge of the 356 wiring variations. YnZ was researching and building these harnesses long before other competitors even thought of getting into the game. YnZ has had a long history with Porsche and many key factory reps in compliling the techincal specifcations and it really shows in their product and customer service.

I personally think they are a work of art. Yes, there are other manufactures that are less expensive, but you know the old saying "you get what you pay for", with the YnZ harness you get MORE than you pay for.


Lets get Started

Most of the harnesses that I have installed involved cars that were complete restorations, so the main tunnel was free of other mechanisms, making the install much easier.

However there are some common tasks that can be done to make the install go as easy as possible.

Interior Preparation

Remove both front seats. The passenger bay is the one I lay in to "massage" the harness up through the harness bay.

Remove the gear shift lever assembly, you can leave the shift linkage rod in the bay.

This next item is very critical. Porsche used very sharp carpet tacks to secure the carpet in place. They used them along the tunnel and other places throughout the interior. Sometimes you find them along the top edge on the right side of the tunnel. Those tacks penetrate right into the harness channel! Even if you remove the tack, it leaves a very sharp burr on the inside. You need to pull these dimples out! If you don't, you will slice the harness sheathing and possibly the wire's sheathing when pulling the harness through the channel.


Here is a simple way to pull those out. Get a sheetmetal screw, about 1 inch in lenght, screw it in just a few threads. Now take a claw hammer and "pop" the screw out.


You may want to "mask" off your dash and any other area you think might get scratched by the wire ends.

Wire harness Preparation

Preparing the harness is based on the direction of pull as the harness is installed. I have only install the harness one way and that is pulling the largest bulk of the wire the shortest distance.

The Harness is divided into three sections:

Section 1 is from the top of the fuse block out to the dash, headlights and dimmer switch.

Section 2 is the "fuse block" intersection.

Section 3 is from the bottom of the "fuse block" out to the rear of the car.

There are smaller "spurs" along the way, backup lights, dimmer switch etc, but these are not difficult to feed to their locations.

Section 1 Preparation

You need to wrap the harness so it can be feed up through the harness bay. When you wrap this section, try to keep it somewhat oval in shape. The flatter the oval the better. As you can see by the photo below, the bay wider than taller. We are going to feed section one from the narrow end up through the wide end.

Start your wrapping from the fuse block section and move out towards the end. This keeps the wire from bunching up. Again keep in mind "Flat oval".

Section 2 Preparation

This the easiest section to feed various "Spurs" to their proper location. The headlights, dimmer switch, brakelight and backup light spur, only the headlight spur needs to be wrapped.


Section 3 preparation

Again start your wrapping from the first biforcation passed the backup light spur and work towards the end of the harness. Be sure to tuck all wire ends in tight, its a snug fit for most models (Speedster is easy, less wire). The photo below shows the bay you have to pull the harness through.


The Pull

Looks like everything is ready for the install. Clean towel to lie on with a rolled one to rest my head on. If your comfortable and not fighting to stay in position, this section should be a snap.

I'll leave it up to you to decide whether or not you want to use "Wire Lube". If you do, use it sparingly.

Start feeding Section One up through the harness bay. You should be able to push the majority of this section through, only having to gently pull from the larger opening of the bay.

The key is how to feed the harness. Push the harness up until is stops, then bend the harness at a right angle to the bay and then push forward. The bending motion is like you are trying to feed wire around a corner. You should not have to force it, once there is a tail showing at the upper end you can work the harness with both hands, one pushing, one slightly pulling. It should look the the photo below when done.

The bar you see in the photo is a piece of lightweight tube steel. I use it to anchor the harness and to help flatten it, so that when the fuse block is installed, there is no pressure on it. If you use the fuse block to "form" the harness you risk the chance of cracking it. I make up the fuse block last to give it plenty of time to form itself.

Section Two

This is the easiest section to feed. It consists of both headlight circuits, brake light, back up light circuit and high/low beam circuits.

Feed each circuit accordingly. Both the High//Low beam and stop light circuits are feed through the large rubber grommet in the diagonal bracing. The stop light circuit feeds through a grommet as well in the fire wall.

Section Three

You will need some string/twine to fish through the channel in the tunnel to assist pulling the harness through this section.

Now I only pull the harness through the tunnel section only. I don't try to pull through the bulk head all at the same time. The bulk head exit can be feed through easily by itself. The "tunnel" pull is tight enough without adding a couple of bends to the pull.

If you want to use "wire lube" this will be the place. I don't apply the lube until after I see the harness poke through the other end. Then I apply the lube as the thicker part of the harness is pulled through.

Once you have completed the "tunnel" pull, you can now "feed" the remaining wire through the tube in the bulk head.

Go ahead now and route the various spurs to their specific locations. While the inside of the cab is all setup to lay in, you might as well start there. Start from the top of the fuse block and route the harness to the wiper motor, ignition and light switch etc., clamping the harness with the metal bands under the dash.

Follow the instructions provided by your harness manufactor for making all connections.



Installing a wiring harness - Part II "Testing the System"