| 00:00 |
In this lesson we'll take a look at the process of planning and designing a professional motorsport wiring harness.
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| 00:06 |
This is a step that many enthusiasts tend to skip over in their enthusiasm to get stuck into building a harness, however at HPA we have a saying that failing to plan is planning to fail.
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| 00:18 |
This is arguably the most critical step and the time spent here will reward you when you start construction.
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| 00:26 |
Let's just start by getting familiar with the spreadsheet.
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| 00:29 |
It is, as we've discussed, a complex harness with quite a few elements, so there's a fair few moving parts to this spreadsheet and not all of them are going to be focused on in depth for our worked example.
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| 00:42 |
Also worth just mentioning here that while I'm using a Google sheet here and as you'll see, some hand drawn elements, really there's no black and white solution that you must use.
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| 00:51 |
Of course, at the top end we might be using software such as Harnware for a lot of our design, Microsoft Visio's another option, really whatever suits, as long as your documentation is solid, robust and something that you can come back to.
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| 01:06 |
So, let's dive in here and what we can see, along the bottom here we've got various sheets for our different elements, for example our M170 which we're focusing on at the moment, the C127, the bulkhead etc and as I've said there are a fair few elements, we'll just scroll along further, we've got our concentric layout, our branching and our PDMs.
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| 01:27 |
So, again lots of things there that we need to have defined and documented, so that we always have a rock solid place to come back to when we are actually constructing the harness.
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| 01:39 |
And usually the amount of time that goes into documentation at this level probably won't actually, be dramatically different to the time we'll spend building the harness, but the time we spend here is going to save us the potential of any mistakes, we're going to also know exactly what we're doing when it comes time to build our harness.
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| 01:58 |
Alright, let's dive in in a little bit more detail here and we'll start by moving across to our bulkhead connector here.
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| 02:05 |
I've already talked about how we've defined this particular connector, how many terminals or locations we need on it and, so at the top here we can see that we've defined the connector that we are using and below this we've also got the boot that we will be using once we've completed the harness.
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| 02:24 |
Now, again we've got a downloadable sheet that will guide you on the correct boot size or suitable boot size for the common connector shell sizes.
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| 02:33 |
Here we've got a section where we can add some notes relevant to this particular harness or connector I should say as well, anything that we need to know.
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| 02:41 |
In particular, we've got a lot of splices going on here which we'll look at in a moment and we've got a note here that says we've got a 22 gauge green wire splice to all of our shields beneath the boot and using a S01-03R solder sleeve.
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| 02:58 |
On these sheets I also like to just add a image here of the actual connector body, so that I've got a visual cue to the pinout.
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| 03:08 |
Now, this is quite important when it comes to designing our concentric layup as well because we'll know which of the terminals are in the centre, so while it's a little bit hard to see here, with this particular connector, we start from the outside with our terminal connector position one or terminal position one and the very centre we end up at position 79.
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| 03:29 |
So, if you didn't have this information available it would make it very difficult to correctly design your concentric twist.
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| 03:36 |
Now, this on the interior side obviously connects to our M170 ECU, so let's just quickly head across to that connector and you can see that the pinout of the M170 ECU, the location of the pin numbers is very very different.
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| 03:54 |
For example, here we start on one side of the connector with locations one through to three and on the other side we end up with 64 through to 66.
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| 04:05 |
So, this is something that's very easy to overlook if you haven't actually added these images into your design sheet or at least taken note of them while you are developing your concentric twist.
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| 04:16 |
As we've discussed here, there's some complexity around our concentric twist with how we're going to do this at the bulkhead and out to the engine bay versus how we're then going to have to work with that design at the ECU end, but there is no easy way around this, it is just going to result in our ECU connector being a little bit messy behind that boot.
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| 04:36 |
Let's head back over to our bulkhead worksheet here and we'll look at a few other elements.
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| 04:41 |
So, if we look here for a start, we've got the pin numbers two and three and you can see that I've highlighted these in a grey colour.
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| 04:52 |
Now, this is simply because these are pass through wires here that actually have nothing to do with the M170 ECU.
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| 04:59 |
You can see that the destination for these is to the C127, digital one and digital two input.
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| 05:06 |
And these are for our reverse switch and our four wheel drive switch and we have the specific destination pins here.
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| 05:13 |
Now, the reason I've just highlighted these grey is just, so that they are a very quick and obvious visual cue as to what those particular terminals or contacts are going to.
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| 05:24 |
And if we scroll down further here, we're also going to see that we've got another couple, again grey and these are our analog voltage input two and our sensor zero volt from the C127.
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| 05:39 |
So, it just clarifies that these are not related to our MoTeC M170 ECU.
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| 05:45 |
I just want to highlight some of the considerations we can make when we are choosing our connector body.
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| 05:51 |
We already know we've got a 79 position connector body here and we know if we scroll down, we are using all 79 of those positions.
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| 06:01 |
Now, just looking at how we have modified that harness here or our harness design, if we look here at pin 75, we can see that we are actually connecting the shield drains for both our ref and sync together as opposed to running them through as individual positions.
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| 06:18 |
Likewise our cam position left and right bank, the shield for both of those is joined together and finally our shield up here for our knock sensors, our two knock sensors, those shields are joined together.
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| 06:33 |
So, if we hadn't done this, that would have required an additional three positions for our connector body which would need to jump up in connector size.
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| 06:41 |
Now, ideally we would want to run these drains through together, but in this instance there really is no downside to doing this, particularly that the sensors, the shielded cables that we are running here are essentially going to the same location, so they're going to be subjected to essentially the same levels of noise.
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| 06:57 |
So, these are some of the little considerations we can make here to help us design our harness around a connector body that is available.
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| 07:06 |
Let's head over and have a look at our bulkhead splices external.
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| 07:10 |
So, obviously these are the engine base splices and we'll start at the very top here and we can see we've got our sensor 5V and our sensor 0V.
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| 07:19 |
We scroll down, we've also got our 12V supplies for our injectors, bank 1 and 2, for our VVT and we've also got some auxiliary 12V feeds as well as our battery negative and then we've got our C127.
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| 07:34 |
So, we'll deal with a couple of these specifically and we'll start by talking about the 5V and 0V A and B and on the M170 MoTeC give us two 5V regulated outputs and two matching 0V.
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| 07:48 |
It is important to make sure that when we are connecting to a MAP sensor for example, throttle position, whatever, something that uses a regulated 5V and 0V, that we want to make sure that we match the A 5V and the A 0V or B, whichever one we're using.
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| 08:04 |
Generally, while these sensors do draw very very low current levels, we want to basically load share across the A and B sensor 5V supplies as best we can.
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| 08:17 |
Let's have a look at our sensor 5V A for an example here.
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| 08:21 |
And for a start we've defined the splice, this is a TE connectivity, D-609-05 which is the one with the yellow coloured band.
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| 08:30 |
We're going to be booting this simply with a small section of SCL which keeps everything nice and tight and simple inside the back of the connector body there.
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| 08:40 |
Obviously, we've got a few of these splices, so things do start to get a bit bulky pretty quickly.
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| 08:46 |
And in order to define that particular splice, we do need to add up the CMA values of each of our conductors, as we can see there we've got four conductors that are going into this splice, that'll give us our CMA value and then we can just match that to the particular splice that will fit that particular CMA value.
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| 09:07 |
Now, the actual wiring here, first of all from our ECU we've got our sensor 5V A supply.
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| 09:16 |
And we need to know where we are getting that from, so the destination for that is pin B61.
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| 09:22 |
So, that's pin 61 on our bulkhead connector.
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| 09:25 |
And we can just go back across to our bulkhead connector, just confirm that, we'll scroll down to pin 61 and we can see that yes that does in fact match our sensor 5V A supply.
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| 09:39 |
Also going a little further here for this bulkhead connector, we can see where that is actually, coming from which is from our M170 ECU of course and that is pin 16.
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| 09:49 |
We could go a little deeper and look at that M170 connector and that would show us the same.
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| 09:55 |
We'll head back to our bulkhead splices and what we can see is where we are actually connecting that 5V A supply to, we've got that going to our TPS, our MAP sensor and our oil pressure sensor supply.
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| 10:09 |
Now, as I mentioned we want to make sure that we are matching that with the 0V A and we scroll down and essentially we can see that's exactly what we've done.
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| 10:19 |
Now, we do have a little bit more going on here in that we've also got our power steering switch, that's not powered, it doesn't need a 5V supply, but it does need a regulator or sensor 0V, so we've got that connected there and we've also got our oil pressure and oil temperature combined sensor 0V that is going to be spliced into that 0V A as well.
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| 10:43 |
Alright, let's scroll down a little bit further here and essentially everything is just the same as what we've looked at, for example our 12V supply to our injectors.
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| 10:52 |
So, we've got one pin coming through that bulkhead connector there that's going to then splice out to the four injectors on each bank.
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| 11:00 |
So, for example here, the 12V supply coming from our PDM, that comes through on the number 43 position on our bulkhead connector and that's going to all of our bank one injectors which is the injectors for cylinder 1, 3, 5 and 7.
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| 11:18 |
If you're wondering about the ignition side of things, we are running 8 individual 12V feeds through the bulkhead connector for our ignition coils.
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| 11:27 |
Coming down here we've also got a 12V auxiliary supply here and that's going to be supplying other elements on the connector, on the ECU harness I should say, such as our fuel composition sensor, our lambda to can unit, our inlet flap actuator as well as our alternator ignition feed.
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| 11:47 |
Coming down here further, again we've got some splices here on the engine base side of this connector for our C127 pass through.
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| 11:57 |
This is for the 0V, given that we do need a 0V reference for our reverse switch and our four wheel drive switch.
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| 12:04 |
Now, this is again colour coded grey for exactly the same reasons we've already discussed, just make sure that it stands out to us and we know that this is the C127, it's not related directly to our M170.
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| 12:17 |
That was just one of 48 lessons taken from our professional motorsport wiring course.
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| 12:23 |
This course is perfect to help you learn the skills of designing and constructing professional or mil-spec style wiring harnesses.
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| 12:32 |
You'll learn the fundamentals of automotive wiring as well as the tools and materials required.
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| 12:37 |
You'll learn about autosport connectors, how to select the right one for your application and how to correctly terminate them.
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| 12:44 |
You'll also learn all of the specific practical skills that go hand in hand with constructing these harnesses.
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| 12:51 |
From here you'll learn a simple 10 step process that you can apply to your own wiring jobs regardless whether you're building a simple sub harness or perhaps wiring your engine and chassis from scratch.
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| 13:04 |
Each step of this process is quick and easy to complete and in no time you'll have a complete harness that's been properly designed, documented, constructed and tested, so you'll have the confidence that it'll work right the first time.
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| 13:18 |
We also include a library of worked examples within the course where you can see the 10 step process being applied in real time on a real wiring job.
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| 13:28 |
This course will be perfect regardless whether you're working on a car, a motorbike or an off road vehicle, the skills are 100% applicable.
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| 13:37 |
If you want to find out more, click the link.
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