Planning and Wire Harness Prep
This is not an Installation Guide! These are articles on how I did the installation in my car. My installation will not work for everyone. I have many things deleted, custom made, etc. I am not responsible for your installation by following these articles.
Now that I had a plan in place of what all I wanted the Haltech to control, what all sensors and other stuff I wanted to run I needed to plan out the wiring. Before I could do that though I needed to figure out where everything was going to be mounted. Since I went with the universal harness I had to find a spot to mount the ECU and the new fuse/relay box. Haltech gives you a good amount of slack on the fuse box wiring to the ecu. I decided that the ECU would mount where the old SRS computer mounted under the armrest. The Elite ecu was pretty much the same size so I only needed to make a bracket to mount it. I integrated the ecu mounting bracket into the rear armrest mount so it was solid.
With the ecu in its place I found that the fuse box was long enough to reach to the spot tinder the dash where the old ecu lived. Using the shift cable hold down bracket, I was able to create a mount to hold the Haltech fuse/relay box and also the CAN bus hub. The ECU wiring bundle runs right down the side of the center console and is zip tied to the side like the stock harness was to make it all nice and neat.
One of the items on my “must have” list was a bulkhead connector that will allow me to completely disconnect the engine harness at the firewall. I purchased a Deutsch HDP20 Bulkhead 47-pin and currently use 41 of the 47 pins. For the interior side of the harness it was built using the universal harness all the way to the bulkhead connector. Then on the engine side I re-used good wires from a couple stock harnesses I had to wire the engine side in. This does allow me to color code most of the stock stuff left to the original colors from the engine wiring diagram. All additional sensors and stuff have their own wiring, either in the form of 3 conductor wire for stuff like pressure sensors, or reusing the left over wire from the Haltech harness for things like the DBW motor.
None of my connectors are soldered. If you look at wiring on most cars they are all crimped. Solder is too brittle to hold up over time with the vibrations, temperature changes, etc. I use Non Insulated Ferrule connectors for all my connections along with Adhesive Heat Shrink to ensure they are water tight. Any time I need to add a connector I strictly use Deutsch Connectors. They are easy to use, watertight and reusable. If you mis-pin something then it’s easy to move pins around on them. Plus they are fairly inexpensive. I keep a couple cases of various pin configurations in the shop.
When building my engine harness there are still some things in the engine bay that will require the use of the stock connectors. Since I was not going to re-use the 30+ year old connectors that were currently in the car and falling apart I needed to source new ones. Luckily this is a one stop shop for all the connectors you will need. Brad over at Sheridan Engineering has all of the connectors you will need and even has kits put together for some things. Just shoot him an email with what you’re needing and he will get you situated.
To make my life easier down the road I have all plugs and individual wires labeled. When figuring out what all the various OEM stock connectors do and have running through them, I started to map out excel docs for each plus and marking the actual plugs themselves with black marker what their connector code was from the wiring diagram “C-53, D-15, etc”. Since I had so much stuff deleted I had a bunch of random plugs and wires that needed to be removed, So I started to go through the dash and interior harness removing everything. Mostly this was ABS, SRS, Cruise control related systems. Some of the connectors that were removed shared wires with some things that I needed to reuse in the current setup, Fuel pump trigger, AC clutch, Etc. So all of those wires got moved to their own Deutsch connector and each wire labeled using a Brother P-Touch. Then to ensure that the labels always stay in place and the writing doesn’t get messed up years down the road, all labels were then covered in Clear Adhesive Heat Shrink to protect the label. I used this method on all my labels to ensure they survived the extremes.
For the engine bay harness, you can get completely lost down the rabbit hole when it comes to building an engine harness, especially when people throw around terms like Milspec, Race Harness, Concentric Twisted, Building motorsport spec harnesses. Well I’m not building a racecar, so for the most part I threw it all out the window. I wanted a clean, easily manageable, easily maintainable harness. Not like you could completely do it anyway since some of the stock connectors don’t meet most of those specifications to begin with.
I started with running wires from every sensor/connector back to where they would meet at the firewall bulkhead connector following a route they would all run that keeps them out of the way and away from heat or abrasive sources. Then each lead would get wrapped in High Heat Tesa Tape, then sleeved using PET expandable braid with the end sealed with the adhesive heat shrink. Each lead is labeled using the above method. At the ends of the lead the Deutsch connector pins were crimped on. I added additional Deutsch connectors for the injectors and coils by the head so that each bank could be disconnected and maintained as needed. For the interior portion of the harness I just used the normal Fuzzy Tesa Tape as I despise electrical tape and the mess it leaves on wires once it gets hot.
Once both the interior and exterior harness was completed I pulled everything out of the car, connected both harnesses at the bulkhead connector and tested every single wire with a multimeter. During the entire harness build process I kept track of every connector, wire color, etc in a Google docs sheet. This final bench test with the multimeter was used to confirm that every wire was where it should be and that every ground wire was grounded and every power wire was only going to power. Building a harness like this from scratch takes a lot of planning and notes. So it is best to break it all down into simple steps. Do one sensor at a time, then the next, then the next. It becomes really easy if you plan and break it out into small pieces of a larger project..