Project SC300 Road Racer: Part 12 – Cabin Fever


Once the bridge harness was complete, it was time to integrate it into the Haltech plug-and-play harness. Tom taped the existing harness to the roll bar to make it easier to work with.

We got a bunch of extra ECU pins from Haltech so that we could get to work.

You can see the pulsed input bridge harness zip tied to the Haltech harness in this photo. We’ve also pulled out some of the pins from the ECU connector on the Haltech harness side. One of these was a signal ground connection from the ECU.

If you recall, Haltech’s Elite series ECUs now incorporate a dedicated signal ground for sensor voltage references. This helps improve the stability and quality of analog voltage references. Since we were adding new and additional sensors to the system, we needed to ensure that we tapped into this signal ground so that we could use it. We also needed to tap into the +5V reference and ensure that we used that, too. Take special note of how the AMP Superseal terminals look. A proper crimp includes wrapping around the wiring insulation as well as a crimp onto the bare, stripped wire.


Tom is splicing the signal ground wire.

The Elite 2500 has three connections that are signal ground. In the main Haltech harness there is a splice tying all of them together. We just chose one that was convenient to splice into in order to break out the signal ground we needed.

We carefully de-pinned, re-pinned, and moved connections on the Haltech ECU connectors. A couple of hours later, our bridge harness was integrated and we could move on to the rest of the cabin harness.


In addition to the Racepak Smartwire Switch Panel, we also had some extra switches for other things.

Since we were including wiring for hazard lights, blinkers, and adjusting the power steering column of the SC300 in our design, we also created a sub-harness for this. The benefit of this sub-harness is that it allows for the dashboard to be easily removed without having to pull connections off of each switch.

The hazards were easy — a simple switch would ground an input of the Racepak, and we would program that input to cause the blinkers to flash.

The blinkers were slightly more complicated, and the steering column was a little more complicated, still.

Leave a Reply

Your email address will not be published. Required fields are marked *