Tag Archives: wiring harness

October 2006 – Electrical

This section is for Ove in Norway.

It’s about time to put the electrical decisions onto paper in a more presentable form. More methodical men than I would have rendered schematics first, traced everything to glassines in layers, and then passed the signed drawings to the next person for enactment … and, of course, improvization. The web pages that follow might even become my car’s electrical schematic. There’s always discussion about Joseph Lucas’s electrical setup for British cars, and I have dug up a quote that may or may not be accurately ascribed to Lucas. “Gentlemen do not drive after dark,” he is supposed to have said. If so, he can hardly have really been the Prince of Darkness, since he would never have been out in darkness, being a gentleman. And yet, I recall a warm night in or near the “scenic Flint Hills” of Kansas when the Lucas electrics in my MG failed and lights became weaker and weaker. I was just lucky enough to pull into an oasis on I-35 to let my battery recharge a while. That MG ate alternators.

I was too young to have been a gentleman, but I learned something about Lucas electrics.

When we removed the harnesses from the Jaguar, they all came out intact. The forward harnesses inside the bonnet and forward of the front bulkhead/firewall has been altered in part to resolve what must have been some starter alterations and to “improve” cooling. Otherwise, the wires were unmolested by owners or repairmen. Time had taken its toll on the cloth looming and cotton and plastic coatings had suffered from some exposure.

I’ve wanted to bring the car back to near what it was in 1963, except for a change of exterior color. But in part because of my old experience with Lucas electrics, I was willing to depart from the original electrical system — especially where the changes would be obscured from sight. I’ve not made all of the electrical decisions even yet, at least in the final connections. I have followed a few principles in this redesign:

  • Add fused circuits
  • Use relays to separate high and low loads
  • Minimize length of wire runs, if possible
  • Minimize use of connectors
  • Localize connectors to blocks
  • Upgrade wire gauge to runs with higher load
  • Use LEDS where it makes sense

At this point, I have a total of 14 fused circuits, twelve of them emanating from the position where the fuse blocks are supposed to be, behind the center dash panel. The other two are for headlights and horns and are situated near the battery and next to the place where the relays for the horns and the headlight beams are located. These relays sit behind the left front wheel splash guard, directly in front of the battery tray. Those two inline fuses couldn’t be placed elsewhere without lengthening the wire runs from the relays forward. I figured it was worth the inconvenience of having the fuses in unusual places to fuse the headlights and horns separately and shorten the wire runs.

I’ve not mapped the locations of the original “bullet” connectors and connection blocks, but I know that in dismantling the harnesses the connections seemed to be everywhere. The wisdom of electrical troubleshooting on the E-Type seems to amount to checking connections and cleaning connectors. Connectors do deteriorate. I wanted to make sure that I could make as few of them as possible from terminus to terminus. I also wanted to concentrate the connections into specific locations.

The architecture of the car and its harnesses determined where the connection blocks should sit, and in fact a couple of them are originally in place. The “bonnet plug” and the internal connection block inside the bonnet are already in place. In essense, the bonnet plug connects one harness to another in a central location. That was the principle that I used in locating connection blocks. I installed two connection blocks — one underneath the left dash panel, near where the flasher is located. This connection block serves to connect the “fore harness” to the “mid harness” (see the illustration), though it also is often connected through the switches and such on the dash panels. The second connection block is inside the trunk and connects the mid harness to the aft harness. I departed from the locatiion of the mid harness by running it entirely along the car’s left side. Because there might be a need at some time to run wires aft through the passenger compartment, I added four wires along the right side. These terminate inside the trunk area and forward of the glove box. If I’m overcome by wanting to add an electrical whatever to someplace after, I figured I’d have a place to grab power or signal.

I’ve used spade-type connectors quite frequently, though bullet connectors still are to be found, usually to make the final connections to, say, a taillight or fan motor. And the complicated wiper motor connector block with its conflagration of bullet connectors is still there (though as yet, I’ve not connected them all up).

Purists might object to the departures. As much as I respect the gentleman, I’m not intending to make the car a monument to Mr. Lucas. I’m hoping that my little changes might keep the lights brighter.

This is part one. More details later.

January-May 2005 – Trunk floor, wiring harness (redesigned)

New trunk (“boot”) floor

The old trunk floor was totally exhausted, with the laminate of the plywood virtually falling apart in thin wooden sheets. The pieces were good enough to stack together like so many playing cards and trace onto a new sheet of plywood. I used 15/32 thickness plywood that was left over from roofing repair on an outbuilding. The original was probably one-half inch plywood, and I will eventually get around to counting the laminate sheets. The only piece of hardware I have reused is the prong that fits forward of the finger hole “handle” for the right side sheet. The snaps are readily available. The original plywood was painted in one coat with what must have been a flat black, or perhaps a black that was thinned enough to soak in and dull. I used Rustoleum flat black that I had left over from another project. The piece matched perfectly and fit very well.

Custom wiring harness

At least in some measure, the data plate was a dalliance — something fit between more mechanical work that could be accomplished either when winter cold was tolerable or spring warmth chased cold away. During those better moments in the garage, we focused on the rear end of the car. As it now sits, the car is pretty much ready for final upholstery, polish, and chrome from the rear bulkhead back. That includes the wiring from behind the rear bulkhead, in spite of the fact that the wiring harness is completely absent forward from that point.

The harness bothered me when we removed it (intact, believe it or not), because it seemed an unwieldy beast. Since wires can extend from the fuse boxes to the rear lights, I imagined the difficulties of troubleshooting and reinstalling a new harness modelled after the old one. In order to get rid of part of the awkwardness of managing the loomed wire, I decided to modularize the harness. The first one is designed to fit the rear section of the car, and it delivers power to the rear lights, the fuel level sender and the fuel pump. The connections forward of the rear harness are through two connection blocks, one an eight connection block and the other a four connection block modified to handle three connections. Both of the blocks have been modified to reflect the actual circuitry. The large block covers the lighting, and the small one is devoted to fuel sensing and pumping. The ground for everything is to the body, either by wire connection or by direct contact. I have all wiring coming to the rear through the harness hole on the left side of the car. I believe this is not standard, since I believe wiring was routed on both sides of the car to the rear.

Aside from the modularizing and perhaps some routing, the harness follows the original. Wires are color coded to the original specification, and they are wrapped in tape. I did depart from the original somewhat by not inserting the little “LUCAS” labels inside the harness, and I used heat shrink tube to seal the ends of the tape in order to discourage unwinding and give the piece a bit of a finished feel. Figuring out where the harness splits off is really just a matter of cutting the wires, laying them out to figure out where they go, and temporarily clamping or taping the general shape.

I’m using “bullet” connectors on the ends for the lighting, but spade connectors are used at the custom blocks. They’re just easier to manage. After crimping, those connectors also get the heat shrink tube treatment.

A very good source for wire is Rhode Island Wiring Service (http://www.riwire.com). They also carry connectors. They will put together a wiring harness for you, and they apparently have done E-type harnesses before. I’ll probably salvage wire from the original harness, too.

I have looked over the original fuse blocks, and I am increasingly tending toward replacing the old blocks with some newer fuse block setup, using the newer plug-in type fuses.