Professional Motorsports Wiring Harness Venture

[crash]

Just a question here...wouldn't one want to keep the shield isolated from the chassis ground? Putting sensor shields through the shell doesn't make sense to me. Please explain why this won't cause interference issues?

[Jay-rod427]

Just a question here...wouldn't one want to keep the shield isolated from the chassis ground? Putting sensor shields through the shell doesn't make sense to me. Please explain why this won't cause interference issues?

The shielding serves zero purpose to the signal transmission of the wires inside it. The shielding simply protects those wires from outside interferrence. But as said it needs grounded, typically to an ECU pin, to keep static electricity from building up, and to give a place for the interference to go instead of into the wires inside it. And as was said it only gets grounded on one end. It has to go through the connector via a contact, or can be grounded to the shell itself with the right parts to continue it's grounding conduction all the way back to where it is grounded. Otherwise not grounding through the pass through connector would break it's continuity chain and the ungrounded portion would build up static charge.

Shielding works in two ways. 1 it physically rejects emi waves by bouncing them off, second it sends them to ground instead of penetrating the wires. Hence the need to ground it. Fuel injectors, and ignition coils are a common source of emi. Their inductive magnetic coils that activate them kick off a pulse of emi. This pulse if picked up by nearby signal wires can make the computer think it got a pulse from a legit source when it didn't.

I'm not sure 100% on the AEM infinity, but most ECU's have a dedicated shielding ground pin position. Holley Dominator, HP EFI, and terminator it's J1 A14.

[crash]

The shielding serves zero purpose to the signal transmission of the wires inside it. The shielding simply protects those wires from outside interferrence. But as said it needs grounded, typically to an ECU pin, to keep static electricity from building up. And as was said it only gets grounded on one end. It has to go through the connector via a contact, or can be grounded to the shell itself with the right parts to continue it's grounding conduction all the way back to where it is grounded. Otherwise not grounding through the pass through connector would break it's continuity chain and the ungrounded portion would build up static charge.

I'm not sure 100% on the AEM infinity, but most ECU's have a dedicated shielding ground pin position. Holley Dominator, HP EFI, and terminator it's J1 A14.

Yes, so our practice is to keep the shield isolated and to use a pin through the connector and ground at the ECU via the dedicated pin. I am still unclear why using the shell would be a good choice as, in our cars anyway, the plug is usually used in an aluminum bulkhead that is riveted to the chassis and therefore the shield would be exposed to the rather "dirty" ground of the vehicle instead of the filtered ground of the ECU. Again, this is just how we have always done it and I am curious as to how this might be done appropriately via the shell.

[Jay-rod427]

Yes, so our practice is to keep the shield isolated and to use a pin through the connector and ground at the ECU via the dedicated pin. I am still unclear why using the shell would be a good choice as, in our cars anyway, the plug is usually used in an aluminum bulkhead that is riveted to the chassis and therefore the shield would be exposed to the rather "dirty" ground of the vehicle instead of the filtered ground of the ECU. Again, this is just how we have always done it and I am curious as to how this might be done appropriately via the shell.

The concept of using the shell doesn't really apply here. In aerospace there is no chassis grounds so it's a dead path except through the mating connector and back to the shielding on the other side back to the source component. Aerospace doesn't use chassis grounds for components as they are a nightmare. Everything has dedicated grounds ran all the way to the power source.

Sorry to muck up this thread with shell grounding the shields. OP is doing it beautifully except for said solder sleeves imo.

Personally I don't use chassis grounds on something built from the ground up exactly as you said you end up with dirty grounds, and the potential for ground loops. I just finished a race car with ALL grounds ran to the ground post. Upon first startup a huge noticeably faster cleaner starter turning over a 585" BBC.

[jamesfr58]

Jay-rod427

I set my ground up as you spelled out in the last paragraph. I have a lead from battery to a ground block and all ground go back to the ground block. Was very good information about grounding and dirty grounds. Always a pleasure to read and learn an few new things from time to time..

[Shoeless]

No worries going off on a tangent with other aspects of wiring. I actually enjoy the fact that a post I started has spurred so much conversation and side discussions. That’s why we are here, to share our collective knowledge and help each other build better cars.

[KGTM]

In general there are several reason for ground and good ground and shields

1. All high speed signals are shield for most part due to impedance requirements, these are signals above 100 Mhz, 50 ohm, 80 ohm 90 ohm and so on
2. Very low level signals like audio inputs like RCA, these are generally only few volts max and very large dynamic range may be 100db, so even uv changes will be noticed as noise or click especially when volume is at high level
3. Stops emission from signals carried on the wires and if not done well it will make thing worse and not better.]
4. Very high impedance input, may be above 100k or so with low level signals
4. if grounded on both end this only works well is sides is isolated which generally is not in car wirings, on must avoid the shield carrying load current
5. Most sensor today are active and not like the old day like a single wire temperature sensor (they used more current than new one) , hence 3 wire, power ( 5V) ground and active output.

Crash, Star grounding is always a good just may add a lot to wiring, chassis is very low resistance and for most grounds connections and should be good enough, but for sensors is best to go to device ground that receives the sensor input or make differential connections if possible.

I like to say I am no arguing here, I want to make sure I did not miss something in my wiring as well as I have no shielding on all my body control stuff, what crate ECU does I do not know, but some that I have cut and shortened did not have any shield.

Mostafa

[Alan_C]

Just found your thread, quite an undertaking. I am putting a 2nd Gen Coyote into a 70 Mach 1. To keep engine compartment clean, I have mounted the PCM in the front PS fender well. Also moving the power distribution box to the interior requiring modifying the controls pack harness and adding connectors to split it. My job is trivial compared to yours. I look forward to going through your thread step by step.

Subscribed!

[Shoeless]

Just found your thread, quite a undertaking. I am putting a 2nd Gen Coyote into a 70 Mach 1. To keep engine compartment clean, I have mounted the PCM in the front PS fender well. Also moving the power distribution box to the interior requiring modifying the controls pack harness and adding connectors to split it. My job is trivial compared to yours. I look forward to going through your thread step by step.

Subscribed!

Welcome aboard Alan!! This is definitely quite the undertaking, but when complete I will have two harnesses (Chassis and Engine) that will be nothing short of a work of art.

[Shoeless]

Got in the new heat gun and boy did that make a difference. Here is what the soldier sleeves look like when properly melted/recovered. Probably could have used just a tad bit more heat to make sure all the red indicator is gone.

[Shoeless]

After playing with the carbon fiber tubing this morning, I decided to spend some time on the chassis harness. Now that the solder splices are good to go, I needed to splice the two ground leads to one and then install a socket before installing in the Deutsch AS connector. Here you can see I have a yellow band closed barrel splice which is good for CMA of 2350-6755, these are all 20 ga wire, which have a CMA 1006 each and I'm splicing 3, so this is perfect. After the splice is complete, I cover it with a piece of Raychem SCL to seal it up.



Now that the ground shield is good to go, I've got to strip and install the sockets on all the twisted shielded cables.



After installing all the sockets in their respective locations, service loops are installed, and a check to make sure this will all fit behind the shrink moldable boot. Note again I'm working from the center of the connector out and these service loops will be further away from the connector. As I work around the connector, the service loops will get closure to the connector.



Now its time to do some twisting of Layer 1 (all the shielded cables) around the Core of CAN twisted cable from the connector to the first branch point. After twisting this layer, I use kevlar lace to hold it all in place. I've also got to introduce some of the other branches into the first branch point per the build plan. From here, I did a test fit in the car and noticed I was a bit off on one branch point, so I got to do a portion of this all over again LOL. Its better to find and set the branch point locations here, as you will see if there are any changes required down the road, its VERY time consuming to take this harness all apart and redo it.

[Shoeless]

Hey guys,

I took some time today and finished the first branch of the chassis harness build. This one 32 pin plug will interface the engine harness and computer to the chassis and has the following functions, all tightly bundled in a 0.450" cross section.

Speed Sensors for all four corners
ECU Flash for programming
Sensor Grounds
Sensor Powers
Tractions Control Sensitivity Dial on the Steering Wheel
Launch Control RPM Dial on the Steering Wheel
Pedal
Vintage Air Full Throttle Switch (can program at the ECU to what ever RPM I want)
Clutch Digital Switch (not used)
3 Step Launch Control Switch (not used)
Log Enable
Low and High Fan Signal as the ECU will control temps and settings and ground to the InfinityBox
CAN Bus Network for Digital Race Dash
Fuel Level to Race Dash
Tach Signal for Knock Detection Equipment while tuning (normally you have to pick up an injector signal at the engine)
One Open
4 Filler Wires to finish off a nice concentrically twisted pattern with the proper lay length.

[Jay-rod427]

Looking good!

[crash]

I know you might not want to hear this at this point and I probably should have spoken up earlier, but it is my practice to run the harness unfinished as far as bundling and heat shrinking at least a couple of hours to make sure all desired components are covered. In other words, no matter how careful I am in planning, invariably there are additions that I make once I start using the vehicle. If you package the harness all up before testing the car...well you are either cutting the harness back apart or remaking the harness again. Neither option is all that attractive.

[Shoeless]

I know you might not want to hear this at this point and I probably should have spoken up earlier, but it is my practice to run the harness unfinished as far as bundling and heat shrinking at least a couple of hours to make sure all desired components are covered. In other words, no matter how careful I am in planning, invariably there are additions that I make once I start using the vehicle. If you package the harness all up before testing the car...well you are either cutting the harness back apart or remaking the harness again. Neither option is all that attractive.

This is a good point and likely something I may do for the engine harness side of things. I can say, before I shrink branch points and boots for every sensor, I will be trying to turn the engine over. The AEM Infinity ECU will give me a "likelihood of ignition" percentage as I crank it. It is essentially checking to see if the Cam and Crank are in sync and will tell me if I am good to go.

I decided to do this harness first as sort of a practice run on checking all my documentation, build plan, and actual execution of the build plan. I found a situation about 9:00 last night that I had one of the branches right after this branch point, that I introduced the wrong CAN Switched Power and Ground leads. I found that I inadvertently labeled two sets of this function the same color IDs, although the branches were significantly different when it came to length of lead. Thankfully I didn't have to tear this branch apart, but it does bring home the idea that you need to check functions of the harness as you go along or as you stated try to run the harness before even putting together to see if you have it all worked out. Similarly, I have taken this harness to the car no less than 10 times to check my branch points, run lengths, and just general idea of confirming some runs are long enough. My nylon rope mock up was a bit off as it didn't do to well mocking up the perfect 90 deg boot that will go on this connector. So I essentially moved the first branch point closer to the connector and that moved everything closer to this connector.

[crash]

You bring up an excellent point on errors. Sometimes it is as easy as reconfiguring a output/input on a "black box" or sometimes just swapping a pin at a connector. If you need to swap the pin and the harness is all buttoned up...

This is actually a regular occurance for me. Last time was that a "black box" (ECU) manufacturer changed up the pinouts on their product but I had built to their previous units and their previous pin out call outs. Major changes and I was SO glad I had left everything loose and tried it first.

Things happen. Sometimes beyond your control. The proof is in the pudding when it is all said and done...and planned and schematiced.

[Alan_C]

All the words of wisdom and experience are appreciated. I will make sure to test before shrinking the boots on the back of the connectors.

[Shoeless]

Took some time during my lunch break today to work on the continuity check after finishing the first branch. Simply take a corresponding Deutsch pin that mates to the socket and create a custom lead for your volt meter. I'm about half done and hope to finishing this check tonight and carry on with the next step of sheathing this section and recovering the DR-25.

[Shoeless]

Finished up the continuity check and everything checked out as expected, so time to move forward. Following the build plan (which is in a repeating Brach, Twist, Sheath, and Boot process) my next step is to sheath the harness section from the Deutsch Body Connector to Branch Point A. Measuring the diameter of the twisted section at .450" lends to 3/4 DR-25 as it has a shrink ratio of 2:1. There is also the question of length. Although DR-25 spec states it won't shrink on its length, I've been taught to add 5%. So I carefully measure from the branch point to the area I know the 90 boot will cover at the Deutsch connector, cut to length, and slide in place.



Now you can shrink a small portion of one end, I chose the branch point as it is a little more critical to me, and then put a piece of Kapton tape over it to hold it in place.



Now shrink the whole length making sure to apply even heat. I use a circular reflector for this, I'll get a pic of that another time.



Now this section is complete. At this point I can now demonstrate one of the huge benefits of this entire technique, it is completely flexible in any direction.

[Shoeless]

I worked on the splices that will be hidden behind Branch Point A on the harness. These are sensor ground and sensor power leads that split and go to several areas in the harness. Then covered with Raychem SCL. The took the harness back to the car to confirm the branch lengths for the leads that will actually go toward the rear of the car from this branch point. Covered them all with DR-25 and shrunk in place.

At this point I'll clean up this branch point, secure with Kapton Tape, measure for the proper shrink moldable boot and get that on order. I'll try to order all the boots I need for my transitions so I don't have to place multiple order.

[beeman]

Briefly, what is the kapton tape for? I have only used it as a sacrificial surface on a glass 3D Printer bed.

[Jay-rod427]

Briefly, what is the kapton tape for? I have only used it as a sacrificial surface on a glass 3D Printer bed.

It can serve several purposes. Holding the wire bundle instead of lacing tape, but in most instances it is to keep the adhesive from shrink products, or epoxy off of the wires. So if need be shrink products can be removed without damaging the wire insulation integrity. Also commonly used to "build up" a bundle diameter if needed to make it an appropriate diameter.

[Shoeless]

Yup, also good as a masking around connectors so as you are building and moving things in and out of the vehicle for test fits you don’t beat up your expensive connectors. See the last pic in post 140. I have Kapton tape wrapped around the forward side of the connector. When you remove it, it will not leave a residue.

[Shoeless]

Got some Sunday morning progress on the harness. Worth mentioning another function of the Kapton tape is assist with strain relief in the branch points. You will see this below.

The progress today is building up the 3 layer twist from Branch Point A to Branch Point B, securing Branch Point A for final boot measurements, and sheath from A to B. I'd really like to work from Brach Point B outward so I can get a boot measurement for this location and order these both up at the same time, so I'll have to do some more work before I order them.

I start out twisting Layer 1 and Layer 2 as seen in pic 1 and 2, worth noting is any time you see violet wiring in my harness, these are all filler wires to fill out the concentrically twisted layers. Pic 3 is securing the filler wires that go to Brach Point A and pic 4 is the 3/4" DR-25 shrunk on the run from A to B. Notice the lettering on the sheathing, the entire harness will read all in one direction, it's all about the details. The last pic is with more Kapton tape as a strain relief of Branch Point A and scuffed up in preparation for shrinking a boot on this transition point. Scuffing the DR-25 allows for better adhesion when apply RT-375 epoxy under the transition boot while recovering. Note in pic 3 all the branches are placed in such a manner that they don't have to cross over each other to get to their final destination.

[KGTM]

That is a lots of wires!

I thought you have ISIS system and that was suppose to removed all these wires.

I hate to debug this baby.

[Shoeless]

That is a lots of wires!

I thought you have ISIS system and that was suppose to removed all these wires.

I hate to debug this baby.

Since I will be running a standalone ECU with WAY more function than a stock ECU, an AEM CD-7 digital race dash, traction control, and countless other features, the additional interface with the engine harness is required. If you read post 132 you will see all the functions that interface with this part of the harness.

No need to debug if you build it right the first time that's why I spent countless hours on the build documentation and check the harness along the way while building it.

[beeman]

I've torn apart a lot of factory harnesses, looked like a child built them compared to this.

[KGTM]

With all these connection you will need a great documentation.

Looks like you are doing great job in that, I need to do same one of these day.

Mostafa

[Shoeless]

Thanks for the kind words and feedback.

Documentation is an absolute MUST for this approach. As you can imagine if you make one mistake on Layer 1 of the first Branch, I'd be in for A LOT of rework to fix it.

[Shoeless]

I started working on the Tunnel Flying Lead branch point this morning. This is a perfect example of the most simplified concentrically twisted pattern. This branch has a core of one 20 ga wire and 6 x 20 ga wires twisted around this core. A rule of thumb if I had the need for a second layer is to add 6 wires to the last layer count of wires in order to determine the amount of wires that would be in the subsequent layer. Since there were 6 wires in layer one, I would add 6 to that to get 12 wires for the next layer, if I needed to. This patter will continue if you had more layers as well, just add 6 to the previous layer count.

This branch is now ready for DR-25 and then I'll start working the branch that goes to the drivers cockpit location.

[Apexspeedtech]

This all just blows me a away. 15 years ago, I owned a professional motorsports electronics wiring shop, and the only way we had to learn was by tearing apart harnesses built in the UK and trying to reverse-engineer the parts and processes. Now there are so many talented people like yourself getting into it, my hat's off to you for the fine work!

[Shoeless]

This all just blows me a away. 15 years ago, I owned a professional motorsports electronics wiring shop, and the only way we had to learn was by tearing apart harnesses built in the UK and trying to reverse-engineer the parts and processes. Now there are so many talented people like yourself getting into it, my hat's off to you for the fine work!

Thank you for the kind words and welcome to the GTM madness, looking forward to seeing the progress on your resurrection.

[Apexspeedtech]

Thank you for the kind words and welcome to the GTM madness, looking forward to seeing the progress on your resurrection.

Yes, and if you have any questions wiring wise, I'm happy to try and help. My former wiring techs have gone on to do work at Space-X, Nissan Motorsports & TRD, I can reach out to them as well. I've also had a 20-year relationship with IS Motorsport & MOTEC; happy to help with anything regarding mil-spec wire, Autosport connectors, etc.

That said, you're already killing it! The concentric twist, use of lacing tape, SCL sealed splices, solder sleeve shield terminations & service loops check all the boxes. If anything: Are you using Mylar or Teflon tape, I can't quite tell but it still looks Mylar. All good, but the newer Teflon stuff seems to work a little better.

I do like your wiring diagram, though the industry standard is more spreadsheets + layouts. I think a lot of this comes from Harnware and other software tools - which by the way I'm totally out of date on. If you have the bandwidth to do all you did in CAD, that'll be a real benefit in the end.

Have you already committed to the AEM ECU? I'm sorry if I missed it in your thread, but what else have you chosen hardware wise? Integration is a main goal of the car I'm working on. I'm going to set it up with 4 "drive modes:" Street, Track, Rain & Valet: 3 on a visible switch, the 4th hidden. We will have different throttle response, traction control, ABS & ride height based on the switch position & other criteria.

-Neel

[Shoeless]

Thanks for the offering of help, you never know when you are going to run across something you may or may not know how to deal with it. Especially from someone with way more experience that I have at the moment to be honest this is one huge learning exercise for me.

I'm using just regular Kapton tape, no Teflon tape on this build, I may have to try some out and see how I like it.

When I first started this venture, I downloaded and studied what was available from AEM. They had some large PDFs of their harnesses to accompany the pinouts in the instructions. I quickly discovered if I went with any aftermarket setup, I'd need to build my own harness to get the functionality I was looking for. So I studied more of the AEM documents and pretty much created my diagram in conjunction with an excel spreadsheet for all the pin outs. I can't remember at what point I gravitated to AEM and really made a decision to go with them. Likely a combination of simply studying their manuals (yes, I read all 400+ pages before I even knew what I was doing, LOL), making the plan for my GTM and what I wanted functionality wise, and then just stayed with them once I started putting in all the work. So I am HEAVILY committed to that at the moment. Custom ECU mounting bracket in place and powder coated, months worth of documentation created, and with the above build being specifically designed for the I/O of the Series 7 setup. Right now I'll have two 12 position dials, one for traction control sensitivity and one for launch control RPM. I'm sure I can blend in some other features depending how I set up all up with the tables in the software. O that's another point, I'll be doing all the tuning on this from scratch. I'd love if someone would rent me load bearing dyno time and just let me run it, but I need to look around for that. Likely all road tuning until I can get to a dyno someone would either let me rent or work directly with one on it.

I'm pretty excited to be finally jumping into build this chassis side harness. This is actually going to be a piece of cake compared to my engine harness, so this is a good practice run for me.

[Apexspeedtech]

I'm using just regular Kapton tape, no Teflon tape on this build, I may have to try some out and see how I like it.

If you want to grab a roll to try it you can get them here: https://www.milspecwiring.com/12-204...RDS_p_880.html

I've done a few AEM Infinity Systems, happy to answer any questions there too. These days I pretty much stick to MOTEC because of the integration possibilities. Do I remember you're someplace in Florida? This car is up in Daytona Beach, tuning is what I do and again happy to guide you and anyone else.

[Shoeless]

Thanks for the link on the tape.

It will be nice to have another builder/tuner around when I get this bad boy fired up and ready to go. Yup, I’m down in Palm City FL about 2 hrs S of Daytona. I actually went to ERAU in Daytona for my BS in Aerospace Engineering.

[Shoeless]

Hey guys,

I got in several boots to continue with the harness construction and our next step is to slide the boots in place and print out all the labels for each of the branch points and put those to the side with each connector that will ultimately be installed.

The boots I picked up are as follows:
1 x 222K152-25-0 For the large Deutsch AS Connector
1 x 202a142-25-0 For the first large transition point
2 x 202A132-25-0 For the next two smaller transitions
Several others for the other Deutsch AS connectors which I will add later

[crash]

Just curious...why aren't you using branched boots?

https://prowireusa.com/c-71-382a.aspx

Here is the three way that would probably work for most of your branches...

https://prowireusa.com/c-121-raychem-462a-boots.aspx

[Shoeless]

Just curious...why aren't you using branched boots?

https://prowireusa.com/c-71-382a.aspx

Here is the three way that would probably work for most of your branches...

https://prowireusa.com/c-121-raychem-462a-boots.aspx

Great question.

The way this harness lays in the GTM, the straight boots that I'm using and the direction that the harness goes off in after the branch are more aligned with straight boots. I thoroughly reviewed exactly how I could branch a couple things out and one "Y" branch might have worked at the first large branch point, but the B dimensions (after shrunk) did not work for my setup. There was also a possibility of a "T" branch at the second branch point, but again the B dimensions were not conducive to the diameter of all the branched entering and exiting each opening. I would have to build up diameter with additional pieces of SCL shrunk over the branch just to make it work.

Worth noting there will be a number of locations when I get to the engine harness build that I fully intended will use T and possibly Y branches.

[Jay-rod427]

And the T's and Y's get crazy expensive! But that ship has already sailed in this adventure. It's crazy how quick the $$$ adds up on a harness like this.