The electrical system is the ‘nervous system’ of the roadster. It includes the signaling system, instrumentation and engine control systems. I think that this will be one of the most challenging parts of the construction given that I really don’t know much about electrical wiring. The ‘electrical system’ will have two parts: 1) the instrument panel; 2) the rest of the electrical system. I started by putting the two parts together but have discovered that the section is too long and varied to be just one section. Additional ‘electrical system’ photos are found in the electrical system photo album.
The main parts of the electrical system are: the main harness, front and rear harnesses, a secondary fuse block for accessories and the ‘engine’ side of the system including the EFI computer. I’ve also created a grounding ‘loop’ that is separate from the ground on the main harness. and that runs directly to the battery ground rather than simply just a chassis ground.
The Instrument Panel section contains descriptions of the construction of the panel out of a blank piece of 0.04” Al, the wiring of the gauges and switches to the dash harness part of the Ron Francis wire looming the covering of the instrument panel.
The Ron Francis wiring harness consists of a dash harness, main fuse panel harness, rear and front harnesses (feeding the lights, etc.) and a sending unit harness. I also purchased a ‘grounding loop’ set of wires from Ron Francis. The placement of the fuse panel is described in the instrument panel section and photos of it are in both the electrical and instrument panel albums.
The main harness:
The main harness is attached to the fuse panel, shown below installed, looking down.
The front harness is attached to the main harness near the fuse panel, just in front of the peddle assembly, and goes through the front firewall vie a grommet.
The front harness then runs along the DS 3/4” chassis element and through the front splash guard.
As described in the fresh air vent section, the power for the Atwood blower is also housed in the front harness. The front harness splits with a cable going to the PS for the PS headlight. The rear harness, which is cached to the main harness, runs though the transmission tunnel. The green and gray wires will go to the transmission.
The rear harness has wiring for the rear brake and turn lights and the license plate light.
I’ve run the cable for the license plate light through the trunk panel on the PS. It passes through the panel via a grommet and will eventually be fed to the license plate light through the trunk lid.
The system will have a master cutoff (Cole-Hersee); the switch is shown in the center of the ‘H’ panel below the instrument panel.
The rear harness exits the area behind the instrument panel through the firewall. Other cables are for the alternator and engine sensors.
The dash harness connects to the main harness behind the instrument panel. The schematic for the dash wiring can be found in the instrument panel section. The white-wired daisy chain is for the gauge light circuit.
The number of accessories exceeds the original dash harness so I’ve added a second fuse block. The lead with the yellow connector is the ground and joins the from harness ground and grounding strip:
One of the accessories is a trunk light, shown below during a test lighting:
The main wiring harness has a single ground to the chassis. Many problems with electrical systems can be traced back to grounding issues. While I’ll use a chassis ground for the main harness I’m also connecting it to a ‘ rounding loop’ that Im creating using a grounding strip, located behind the instrument panel, that is directly connected to the battery ground (the smaller of the wires below leading to the right of the junction bolt.
The secondary fuse block is connected to the grounding system via the grounding wire jumpers (below). I’ve used dielectric grease at the bolt connection joining the leads.
