Wiring a race car from scratch is a time-consuming process, but it affords the opportunity to make each wire the correct length, gauge, and of a higher-quality material than was used in the factory harness. This ultimately results in lighter, more reliable wiring that is easier to troubleshoot and more aesthetically pleasing. There are three main harnesses that need to be built: the engine harness, the data harness, and the chassis harness.
Before we could begin building the wiring harnesses, the electronics had to be chosen and mounted. The MoTeC M800 ECU, MoTeC ADL2 dash logger, and MoTeC PDM 32 power distribution were all chosen. The M800 offers a wide range of capabilities, including a very capable traction control that may prove beneficial for this project. The ADL2 is a very powerful data logger and dash with extensive input and output capabilities. For example, it can output the speed signal required by the EPS (Electronic Power Steering Module). Finally the PDM 32 replaces the need for fuses and relays. This solid-state power distribution module provides eight 20-amp and twenty-four 8-amp outputs that can be fully configured and triggered by conditions set from any of the information available on the CAN bus. So if the ADL2 is logging diff temp, a condition can be set to turn on the diff fan and pump once a certain temperature is reached. The PDM also logs the condition of each output so it’s possible to monitor current draw and see and address potential issues before it’s too late. To secure the M800 and PDM32, I fabricated a sheet-aluminum tray that is secured to the dash bar of the rollcage, which also carries the EPS module. This keeps the wiring hidden from view and makes sure nothing is damaged when a passenger is strapped in. The ADL2 is mounted to a custom laser-cut bracket that attaches to the steering column. With all the components in place, it was time to start building the wiring harnesses.
For our engine harness, we enlisted Chase Bays to build one of its top-of-the-line custom harnesses with Raychem DR25 jacketing and a firewall quick disconnect. Chase Bays offers harnesses for a wide range of applications and can custom-build a harness for pretty much any engine/ECU combination. Our harness came complete with provisions for the extra AEM engine sensors (IAT, fuel pressure, 3 bar MAP, 150-psi oil pressure, 2x2,000-psi front/rear brake pressure) as well as four wheel speed inputs and boost control solenoid output as requested. Another nice touch is being able to order the harness with the correct injector connectors, eliminating the need for often problematic adapters. Chase builds all of its harnesses to offer a tucked look, opting to run the injector wires up through the manifold as opposed to along the fuel rail. Installation of the engine harness was a straightforward plug-and-play affair. Once the correct location was determined, a hole saw was used to create the needed opening in the firewall, and then the weather-tight disconnect was simply tightened in place.
Next up is the data harness, MoTeC offers a mil-spec basic harness that is a great starting point. From here I simply depinned what wouldn’t be used and added the wiring and connectors needed for front/rear suspension position potentiometers, steering position, shift light module, three-axis accelerometer, fuel level, backlight inverter dimmer, GPS, two beacon mounting locations, and a USB communication port for download. As per MoTeC’s recommendations, 22-gauge Tefzel wire and Raychem DR25 heat shrink are used throughout. A DMC crimper with the correct dies is used to crimp the pins for the autosport and DTM connectors.
The final harness is the chassis harness and is still in the works. This harness runs power outputs from the PDM32 to the headlights, taillights, fuel pumps, rad fan, diff pump, trans pump, diff/trans fan, ECU, ADL2, Can Gateway and keypad, and more. The CAN keypad is a neat product that replaces conventional switches with a CAN-based keypad. It gives 15 fully configurable keys that have indicators showing the status of the output. In addition to the ability to use conditions to turn on the PDM outputs, the CAN keypad can be used to manually turn on an output at any time. This keypad requires what is called a CAN gateway that converts the signal output to be compatible with the MoTeC CAN devices.
Power from the Odyssey PC680 battery is supplied via four-gauge wire, and battery negative is connected to a silver soldered brass ground point installed before paint. Additional ground points at the front and middle of the car are used to ensure excellent ground paths and require much less wire than if running everything back to the battery. A solenoid-type disconnect is used on the positive side in case of emergency. This allows for multiple remote switches to be run in series that any of which can shut down all power at any time. One is mounted with the fire switch on the cowl at the base of the windshield and on the left side of the instrument panel where it can be reached through the driver window or by the driver. The output from the Solenoid then feeds the EPS fuse box, starter/alternator, and PDM32.
With the wiring nearing completion, project S2000 is coming ever closer to firing up and getting on track. Be sure to follow along as the final touches are put in place.