Well, in what seems like an endless process, today we’re going to continue looking at the main wiring looms for our FZ12 project.
I have to admit, this part of the project really surprised me about just how long it would take and how much was involved. I guess in the past my car projects have either been production car modifications or in the case of our NSX race car, we started the wiring from scratch, but I didn’t do a lot of the wiring so didn’t really have a good appreciation for just how much was involved.
My friend Lance agreed to help since he had more experience with building wiring looms with the specifications we wanted to use. For those who haven’t read you can read about the first part of the wiring build here first. FZ12 Wiring – Part 1
At the end of the last episode we had only completed what are called the bulkhead ends of the engine loom. They are a waterproof sealed connector that attaches to the rear firewall / bulkhead of the FZ12 and that allows the wiring to be passed through into the cabin to be wired into the ECU and PDM.
These bulkhead connectors were split into left and right bank of the engine since there was so many wires on each side. In total we expected to only need 2 bulkhead connectors originally, each with 47 pins each, but due to the amount of extra sensors and devices on this car we needed to add a third and then a fourth bulkhead connector to the rear. We had spent quite a few days sitting down walking through all of the options, sensors, lights, switches etc that we could think of, however there was plenty we missed so it’s been a bit of a moving target to some degree, but Lance’s experience meant that he allowed for those mistakes or changes and so we were able to adjust fairly easily.
So here we are with the other end of the main engine loom still to finish and apply connectors.
One of the terms I’ve used in this build so far is “V12 tax”. What I mean by that is that in a normal engine you only usually have 4 or 6 cylinders to worry about, not 12. Accordingly that translates to more, lots more of everything including wiring and connectors !
2 wires for each injector and 3 wires for each of the Honda coils we fitted some time back.
A very important part of the entire loom is to make sure water and other contaminants don’t get into the connectors. That is why you will notice that on every area of the loom there is sealed heatshrink or a rubber sealed connector such as these for the ignition coils.
These photos start to give you an idea of just what we’ve got ourselves into with this build ! So many wires and this is just the engine which actually isn’t even half of the wiring required for the whole car.
Nestled right down in the ‘V’ of the engine you can see the 2 engine knock sensors, one on each side of the engine and offset front and back also to make sure we get the best picture of what might be going on if anything bad starts to happen.
All finished for the engine side of things at least !
Next was to get started on the 3rd and 4th bulkhead looms which are to run things like suspension travel sensors, ride height sensors and controllers, rear lights, airbrake, exhaust muffler system etc
That little paragraph above makes the whole process seem like it’s really quick and easy when in fact each of those bulkhead looms took approx 15-20 hours each to make, that’s just the bulkhead end and the heatstrink for the main part of the loom, there’s still more hours needed to finish the other end, heatshrink, label and terminate with plugs !
Lance and I so far have spent close to 5 months of part time work to get this far.
As I mentioned earlier on, the amount of wiring had taken us both back a bit, as although we felt like we’d planned things out pretty well (15 pages on a spreadsheet) and there was 3 of us in total that went over that spreadsheet, we still missed things. Although we were able to get around the extra wiring needed what we couldn’t work around was the need for an extra Motec PDM (power distribution module). I will cover off the functions of the Motec PDM for those who don’t know about them in a seperate episode.
Once we had this unit we could get started wiring from the cabin side of the bulkhead connector to the devices (ECU, PDM, polarity reversers, earthing points and Viking suspension controller).
With so much wiring coming to one place, there’s no “pretty” way to make it all work, and although it’s not finished in these photo’s it is pretty close and I think given the amount of connections it’s come out pretty well. There are close to 300 connections and ……wait for it……. 900 metres of wire in the entire loom for front and back. Luckily Lance made sure that I used Tefzel wire which is a very small and light weight wire that can cope with more current than most wire and exceeds the spec we were looking to meet with our loom. Clever guy that Lance !
One thing I hadn’t realised as we planned and executed this loom was the amount of ground (earth), sensor ground and +5V connections that we would have. Each analogue sensor (and there’s plenty of them) needs a wire back to the sensor ground and also one to the +5V. To make this as tidy as possible I used my 3D printer to create a bus bar where we could mount everything to in a tidy manner.
We basically connect one end to the +5V connection and then all of the other bolts retain multiple incoming +5V connections. The process was the same with the ground and sensor ground.
You can see how these are used in some of the photo’s above.
So this brings an end to this episode, but the wiring dynasty will continue later as we progress other parts of the car and get closer to starting the engine !
Please feel free to comment or ask questions, I really love sharing and discussing our build and cars in general with other readers.
There’s a newer entry in this story, please click here – FZ12 – Part 30
If you’ve missed the last part of our story then click here FZ12 – Part 28
or if you want to go right to the beginning then click here FZ12 – Part 1