Professional Motorsports Wiring Harness Venture

[Shoeless]

Shane is right you must have a lot of patience for sure, unbelievable, it looks fantastic, know I did not do that good a job. Keep up the post and work it is fascinating to see your progress and how to build a professional wire harness.

Thanks James!!! I'd like to think I have some level of patience, but I think my wife would argue opposite that LOL. I have lost plenty of sleep over thinking I have already missed a note somewhere or one circuit somewhere in my diagram. I have only started to scratch the surface of actually constructing this wiring harness (pig tails for the sensors mostly), but the amount of planning that goes into this is unbelievable. I'm sure it gets easier and faster the more you do this, but for me being my first time its quite time consuming.

[beeman]

I may have missed it, which soldering technique are you using? I typically do the twist-solder-fold technique, have looked at the NASA technique. What do you prefer?

[jamesfr58]

I know how that goes, after making sure I had wire pulled for everything, well I don't, forgot to add the wires for day time driving lights (LED's) that are going into the headlights. Since I am working on them now it became apparent that I just forgot to pull these wire in when I took the headlight wire to the from of the car. Oh well, now I have some more wiring to pull and of course finish the headlight wiring when the hood is mounted.

[beeman]

I know how that goes, after making sure I had wire pulled for everything, well I don't, forgot to add the wires for day time driving lights (LED's) that are going into the headlights. Since I am working on them now it became apparent that I just forgot to pull these wire in when I took the headlight wire to the from of the car. Oh well, now I have some more wiring to pull and of course finish the headlight wiring when the hood is mounted.

For the DRLs, I used a single 5 pin relay for both the headlight low beams and DRLs. Hook your DRLs up to pin 87a (normally closed), your DRLs will come on when the relay gets powered up by your key or battery switch. When your relay gets power across the coil (when you flip on the headlight switch), you will get voltage (pin 87) to the headlight lamps and the DRLs will turn off. May save you running some wires...

41cLL1VYmpL_500x305.jpg

[Shoeless]

I may have missed it, which soldering technique are you using? I typically do the twist-solder-fold technique, have looked at the NASA technique. What do you prefer?

Hey Beeman,

Are you referencing when I'm creating the pig tails for the sensors (soldering the wire to the actual metal lead in the sensor plug socket, similar to pic 1 and 3 of post 38) or soldering wires for general wire to wire connection? The only solder that is in a motorsports grade harness is in the pig tails or if I'm using a solder sleeve to connect the shielding sleeve on twisted shielded wire to a wire to then be able to pass it through an Auto Sports connector (pic 3 of post 77) or ground it to the ECU pin. For any wire to wire connections, I'll use closed barrel splices as seen in pic 2 of post 21.

Thanks for the tip on the DRL, I was scratching my head on how to get that to work.

I know how that goes, after making sure I had wire pulled for everything, well I don't, forgot to add the wires for day time driving lights (LED's) that are going into the headlights. Since I am working on them now it became apparent that I just forgot to pull these wire in when I took the headlight wire to the from of the car. Oh well, now I have some more wiring to pull and of course finish the headlight wiring when the hood is mounted.

I almost forgot DRL, thanks for the reminder.

[Shoeless]

I know how that goes, after making sure I had wire pulled for everything, well I don't, forgot to add the wires for day time driving lights (LED's) that are going into the headlights. Since I am working on them now it became apparent that I just forgot to pull these wire in when I took the headlight wire to the from of the car. Oh well, now I have some more wiring to pull and of course finish the headlight wiring when the hood is mounted.

Hey James,

What DRLs are you going with? I just found these as a pretty slick kit. It looks like the function is either on or turn signal activated.

https://www.amazon.com/CARLITS-Flexi...NsaWNrPXRydWU=

[beeman]

Ah, I see, so no end-to-end soldering, just crimp connectors with heat shrink overlay. What are pro's of doing that over soldering? Looks a lot quicker anyways, if you have the right crimper, I'm assuming splices are cheap but crimper is $$$.

[beeman]

Hey James,

What DRLs are you going with? I just found these as a pretty slick kit. It looks like the function is either on or turn signal activated.

https://www.amazon.com/CARLITS-Flexi...NsaWNrPXRydWU=

Reviews look good for those until you click "show recent revews"..





These guys have much better quality stuff, I'm using one of their switchbacks on my GTM. Typically 3 year warranty.
Cheap Chinese LEDs will have you ripping your headlights back apart, I didn't want that hassle.

https://www.theretrofitsource.com/rg...rips-universal

[Shoeless]

Beeman,

Thanks for the heads up on a better quality product out there for the DRL. I'll bookmark them in my BOM and refer back when I'm ready to purchase.

On the topic of closed barrel splices versus soldering for end to end connections, or any soldering for that matter, you are essentially taking a multi-strand wire and once soldered you are making it a single solid core solid wire. When you do this you are essentially making a flexible wire brittle as you have now taken away all the strain relief that comes with a multi strand wire. Over time the vibration in the car will cause the solder joint to fail where the closed barrel splice will survive.

When it comes to cost, those little closed barrel splices are pricy compared to other connection options out there. If purchased separately the Red size in the pic above are $2.00 each (depending where you get them). I picked up a large variety kit of splices for around $300, link below. This was a better start for me as I didn't know exactly how many and of what size I would need. You are spot on for the crimpers, expensive as all can be, but when done right its the best connection available. I think all told I spent about $400 for three crimpers to do everything from these mini-splices, to the larger Molex splices, and all the way up to 1/0 battery cable. I will say I think the investment is worth it, at least for me, being able to use the proper tooling to make large 1/0 battery cables and then switch up to splicing 5 x 20ga wires to 1 x 12 ga wire is an absolute pleasure.

https://racespeconline.com/collectio...ve-starter-kit

[beeman]

Beeman,

Thanks for the heads up on a better quality product out there for the DRL. I'll bookmark them in my BOM and refer back when I'm ready to purchase.

On the topic of closed barrel splices versus soldering for end to end connections, or any soldering for that matter, you are essentially taking a multi-strand wire and once soldered you are making it a single solid core solid wire. When you do this you are essentially making a flexible wire brittle as you have now taken away all the strain relief that comes with a multi strand wire. Over time the vibration in the car will cause the solder joint to fail where the closed barrel splice will survive.

When it comes to cost, those little closed barrel splices are pricy compared to other connection options out there. If purchased separately the Red size in the pic above are $2.00 each (depending where you get them). I picked up a large variety kit of splices for around $300, link below. This was a better start for me as I didn't know exactly how many and of what size I would need. You are spot on for the crimpers, expensive as all can be, but when done right its the best connection available. I think all told I spent about $400 for three crimpers to do everything from these mini-splices, to the larger Molex splices, and all the way up to 1/0 battery cable. I will say I think the investment is worth it, at least for me, being able to use the proper tooling to make large 1/0 battery cables and then switch up to splicing 5 x 20ga wires to 1 x 12 ga wire is an absolute pleasure.

https://racespeconline.com/collectio...ve-starter-kit

Thanks for sharing your knowledge!

[crash]

Yep, solder is a no-no in wire looms. The only exception for me is in large(small gauge) wire for batteries and such. In those cases I use both crimping and some solder. The thinking is that because of the large size there is relatively low bending anyway, and the solder helps ensure the electrons are transferred from the inner copper out to the connector body with the least resistance possible. Generally speaking, connections of all types should be kept to a minimum and solder, IMHO, only used on really large cables that will see high amperage rates, and then crimping should be used as the primary fixer.

Can't say I haven't repaired a wire here and there though, and in doing so I fold the wires back on each other so they loop together and are in a straight line. Then I twist the exposed wires back on thelselves. Then solder. Then heat shrink. I splice so rarely that I do not own any of those splicing terminals.

[jamesfr58]

Dave,

Thanks for the information on the DRL wiring and the relay reference. Never thought about using a relay since I am using the Infinity Box System but know I can add on into the the system even using the Infinity Box.

[jamesfr58]

Sean,

We must think alike at times, I actually have a set of light as you describe above on order, not from the same company but same type of LED lights to use as DRL lights. They are white DRL and amber sequential turn signals. Going to check out Dave's relay idea but not sure I can make work with Infinity Box but as mentioned I know you can add relay to the system. I had another way to get the DRL to come on when the ignition was turned on but they would remain on even with the head lights until you turned the ignition off so the relay idea may be just the ticket.

[Shoeless]

I figured it was time to finish up the wiring on the steering wheel button plate this morning.

The first step was to prep and install some Raychem ATUM over all the splice joints to clean it up a bit. Where the four branches come out of the top there is a zip tie for strain relieve and I filled inside the branch with ResinTech RT125 to totally seal things up.


Next it was time to cut to length, strip, and install the pins on the ends of the wire. This was then followed by inserting the pins into their appropriate position in the Deutsch AS Connector. You begin inserting the wires into the connector at the center and work your way outboard. Similarly strain relieve loops at the center start farther away from he connector and then work towards it as you get to the outside pins.




Followed by installing and shrinking down the 90 deg Raychem semi-rigid boot.





Once the RT125 dries, she will be ready to install.



While the RT125 is drying, here is a final pic from a prior test fit up.

[VRaptor SpeedWorks, LLC]

Very cool!! Definitely looks production!

[Shoeless]

Very cool!! Definitely looks production!

Thanks Shane!!! I really enjoyed planning this out and building it. Now I’ve got to do the mating side on the steering column and clock spring.

[jamesfr58]

Looks really great Sean very professional will look production as Shane said when you are done.

[beeman]

Elegant and exotic

[Shoeless]

Thank you James and Dave for the kind words. I'm really enjoying this new approach to wiring up my GTM and sharing it with the forum. I can't wait to start the process of the engine harness, which should be pretty soon as I have most of the mechanical items installed.

I built the pig tail that I'll attach to the clock spring yesterday and let the RT125 cure overnight before I did a test fit this morning. Everything looks as I planned it out and you can barely see the Deutsch connectors behind the steering wheel, so I'm pretty darn happy with how this is turning out. The only thing left is to cut a hole in the Momo adapter boot, pass the pig tail through it, and splice to the clock spring and I can check this item off as complete on my todo list.

[jamesfr58]

Looking good.....

[Shoeless]

I finished up the steering wheel installation and splicing all the wiring to the clock spring. Started out by cutting a little hole in the Momo adapter, fitting the pig tail I built inside, and then started splicing to the clock spring. All while double checking and marking off on my documentation when each circuit is completed.





Once everything was spliced it was time to put the Momo cover on and install the wheel for final fit checks. Heres a shot of the top and bottom of behind the plate and a final LED light check from the front. The Deutsch AS connector tucks up nicely behind the steering wheel and everything is secured with a couple zip ties for final strain relief.







Time to finally move on to creating a harness from scratch. I'll be starting with a smaller harness, specifically the chassis side of where the engine harness connects to as a practice run. I will use all the same steps on this harness as I would for the engine harness, so this will be good practice.

[beeman]

Congrats on wrapping up the steering wheel plate!
What are you using for a fuse box?

[jamesfr58]

Look real good a very nice installation, you have more patience than I have for sure. Great look !!

[Shoeless]

Congrats on wrapping up the steering wheel plate!
What are you using for a fuse box?

Thanks Dave!!! I'll be using a GEP fusebox for the engine harness construction.

Look real good a very nice installation, you have more patience than I have for sure. Great look !!

Really appreciate it James!!! I wouldn't think I'm a patient person, but this wiring is sure humbling me LOL. Glad my final product here on the steering wheel button plate came out as I envisioned it in my head a number of months ago.

[crash]

Just a little update on Prowire... Nick finally got out of CA and moved the operation to Arizona. I don't blame him. Not real convenient for me as I used to "pop in" and grab what I needed, but I do understand not wanting to own a business or live in California. This state, politically, SUCKS! Now they are talking about trying to tax those that leave the state for a future 10 YEARS!!! These people are insane...but I digress.

Fortunately they have increased their offerings and have also stream lined their website.

[Shoeless]

Just a little update on Prowire... Nick finally got out of CA and moved the operation to Arizona. I don't blame him. Not real convenient for me as I used to "pop in" and grab what I needed, but I do understand not wanting to own a business or live in California. This state, politically, SUCKS! Now they are talking about trying to tax those that leave the state for a future 10 YEARS!!! These people are insane...but I digress.

Fortunately they have increased their offerings and have also stream lined their website.

Perfect timing. I was just reviewing/creating my build documentation for the chassis side engine harness interface and putting together another order for them.

I can't believe the BS that California is trying to pull these days. Absolutely insane!!!

[Shoeless]

The time has come that I finally kick off building the chassis side harness that my engine harness will interface with. This will be great practice before I tackle the engine harness and will allow me to follow all the same steps I'll need to follow on the engine harness.

Here are the steps I'll be following and sharing along the way for building a professional motorsports harness.

Step 1: Spec and Circuit Design
Step 2: Layout, Branching, and Routing Design
Step 3: Documentation Detail and Concentric Layer Design
Step 4: Generating Construction Plan
Step 5: Follow the Construction Plan
Step 6: Connector Boot Prep and Labeling
Step 7: Terminal Crimping and Connector Installation
Step 8: Continuity Testing
Step 9: Transition and Connector Boot Recovery and Sealing
Step 10: Final Install

I've shared my Visio Pro Harness Construction document before and have used that and an xcel file to complete step 1. There have been several changes over the last month or two, but I think I finally have it all figured out and am ready to proceed. The excel file lists every circuit, wire color, wire size, connector type, boot part number, pins used,...literally everything needed to actually build each of these harnesses. I've use this to purchase every connector, pin, multiple spools or wire, tools,...nearly everything I'll need to complete the construction. I'm sure I'll need more supplies along the way, but I have enough to make myself dangerous

Step 2 is physically choosing the routing path for the harness throughout the car. You can do this by using small diameter rope as it will mimic the physical size of the harness and also has nearly the same bend radius. I actually did this part twice as I wasn't too confident on my first try. You essentially start at the most complex connector, in my case its a "bulkhead" connector that will interface with engine harness and then run the rope to the longest point of the harness. In my case its all the way up to the front of the car, into the driver's side cabin, and to the location of my CD-7 Race Dash. From there you can create several branch points along the main branch where you need breakouts for other sensor, actuators, or interfaces. I have items like all 4 wheel speed sensors, DBW pedal, Log button, CAN network interfaces, and a few more. Once I had this mock harness all in place in the car, I took about 20 photos so I know exactly how I routed it in the design phase and how it will be installed when completed. Here are a few pics.

This is the "bulkhead" connector, CAN interfaces, and 6 port CAN Hub



Followed by a couple pics by the drivers cockpit.





Now I removed the mock harness, making sure all the branches stayed in place so that I could measure out of the car.



The next step is to create a diagram for the whole harness with measurements of each branch. This will feed into the following steps when I start to prepare the wire for the harness construction. It's tempting to want to start cutting wires, but not yet, there is more planning work to do. If you look closely at the following diagram, I have two measurements for each branch. The physical measurement is in parenthesis and the length that I need to cut the wire is to the left of this number and is 20% more than the physical measurement. This is done to make up for the loss in the concentric twisting that will take place during the construction phase.

[Shoeless]

I'm now mostly through Step 3 with completing the Documentation Detail and Concentric Layer Design. Starting at the "bulkhead" connector, going layer by layer, and documenting every detail for each branch of the process. If you have been following along, I have been building test branches that mimic this harness so I know what to plan for. This document has all the detail I need (what wires are on what layer, the function of that wire, twist direction, laced or not, diameter of DR-25 that will go over each branch, final diameters of each layer, ...damn near everything you need.

I've got a few things to clean up in this document before I move to the next, but I'm going to go ahead and start Step 4 Generating the Construction Plan.

[VRaptor SpeedWorks, LLC]

Wow....that is a mind-blowing amount of organization and preparation!

[Shoeless]

Wow....that is a mind-blowing amount of organization and preparation!

You're tell me LOL. The amount of time I've dedicated to this is insane. When I first started taking the classes to learn this, they straight up said it will take 4x the amount of time when compared to creating a "club day" harness. I can attest, that is a no BS statement.

Just think, this is actually a fairly "easy" harness. The engine harness is going to be a MONSTER to do.

[Shoeless]

I was super stoked this morning to get up early and officially kick off starting the chassis side wiring harness for the GTM, unfortunately I wouldn't make it very far. I found an old hobby table I had kept my hands on from my RC car days that I decided to use for a separate work station just for this project. Not ideal, but it will work. I got all my supplies lined up on the pool table edge, all my tools and splices on the left, and documentation to follow all printed out.

First step was to twist about 15 ft. of CAN communication wire that I will use on this harness and the engine harness. After twisting what I needed, I cut the length for the first segment of this core, installed the pins, and installed in the Deutsch AS connector. Note, you want to start working from the center of the connector out and your service loops should be further from the connected for the wires in the center of the connector. As a guide I cut out a silhouette of what the shrunken boot will be to make sure I keep everything behind the boot.

The next step was to build a sample of grounding two twisted pair cables to one ground wire using a Raychem Solder Sleeve and this is where my problems started. When you fully melt these solder in these sleeves, all the red coloring will disappear. As can be seen there is still some semblance of red and therefore not a complete soldered connection. I got the size on the connection done enough to hide behind the boot, but I've got a problem I need to figure out. Oddly I did a handful of samples, some would work, and then I go to my cut cables and try it and nope, the solder wouldn't flow. I obviously have an issue with my heat gun. Sure enough when I would crank it up to 1100 and then check the temp and was only reading about 750. These solder sleeves need about 900-950 so I need a replacement. I decided to step up to the Ideal 46-204 Heat Elite Plus Heat Gun, probably should have bought this heat gun to start with, but oh well. So everything is on hold til that comes in.

[Jay-rod427]

Personally I'd skip the solder sleeves, and do open barrel crimps with a short piece of shrink tubing. Solder just makes the wires stiff and brittle prone to cracking.

[Shoeless]

Personally I'd skip the solder sleeves, and do open barrel crimps with a short piece of shrink tubing. Solder just makes the wires stiff and brittle prone to cracking.

Normally I would totally agree with you here on this, but there is really only 2 times that solder is used on a motorsports grade harness.

1. When you solder leads to a sensor or actuator and then pot with potting compound and make completely encapsulated.
2. Raychem Solder sleeves like these.

An open barrel crimp option you mention is more "club day" level harness construction. Plus, I'm trying to ground the shield on two twisted shielded cables with one ground lead to feed through the AS connector. Not to mention I get to buy a new tool that is designed for this level of construction with the controls and features on the heat gun, plus I love new tools

[Jay-rod427]

#1 sure as there is no other choice.

#2 I work in aerospace communications, and solder is frowned upon whenever possible. My company specializes in eliminating solder sleeves and terminating shielding wires, but that's a whole other story. Even the academy recommends against them whenever possible. Mechanical crimp joint is proven over and over again when done properly to be superior to solder.

You could even go one step further and just crimp both the shield wires together directly into the contact for the AS connector if the contact is big enough since it's only
2 shield wires on this harness. You couldn't do this on say an AMP superseal ECU connector since the contact is inserted with the wire pressure, but on the AS connector the contact insertion tool can push the contact in to seat. Since the shield braided wires have no rigidity.

High quality reliable heat gun absolutely should be in the arsenal for ya! Hot enough to activate/shrink certain products, but controllable enough to not damage other things.

When you get to other areas you are going to have to utilize open/closed barrel splices. "motorsport" level or not. Say your ECU sensor 5v references. You'll have many 5v sensors that need this power feed, but limited outputs on the ecu. It is very common to split a single 5v ref output to 4-5 sensors. 1 wire in an open barrel crimp becomes 5 wires. Same with sensor grounds. Low current wires split very commonly.

[Shoeless]

Very cool, who do you work for? I've been in Aerospace Manufacturing for the last 15 years and currently work at Pratt and Whitney in West Palm Beach FL.

I'll actually have 4 x twisted shielded pair cables in this side of the harness. My plan was to Raychem Solder Splice two together to one ground lead, repeat this for the other two cables, and then close barrel splice the two ground leads to one, and then pin in the 32 position AS connector. Unfortunately, all positions are taken up with my plan so I have to get all 4 shields into one 20 ga pin.

Most definitely will be using closed barrel splices for splicing Sensor Supply (+5V) and Sensor Ground signals throughout both this harness and the engine harness when I get there. Even with the AEM Infinity Series 7 ECU I've got there are limited pins for these as you noted.

[Jay-rod427]

Way easier to closed, or open barrel splice all 4 at the same time into a single contact lead. Less bulk and clutter in the bundle. I work for a small company called Isodyne. EMI/RFI connector accessories. We make the rugged functional military versions of the knurled nut on the back of that AS connector. Our system shield drain wires are grounded through the backshell/connector bodies so a contact in the connector isn't needed/wasted.

[Shoeless]

Very nice. One of our applications on our expendable turbojet platform (TJ150), which by the way is the only harness we build in house, drains the shield to the back shell.

[KGTM]

Damn question, what are you sheiding from?
Most car sensor have large outputs and should not need shielding, the ground connection is more important than the shield.

[Jay-rod427]

Damn question, what are you sheiding from?
Most car sensor have large outputs and should not need shielding, the ground connection is more important than the shield.

Pulse signals are very susceptible to interference. Any speed signal is a pulse based signal. Wheels sensors, driveshaft sensor, crank signal, cam sync, Wideband O2's even. Where the computer is processing VERY fine signal pulses at a very high rate outside noise making that signal dirty can cause issues. That's also why those wires are twisted pairs to keep the wire from causing noise from itself. The signal and feed being twisted cancels out the interference from itself. The worst offenders are magnetic pickup sensors as they read magnetic interference intentionally, and shielding reduces external magnetic interference. Modern Hall effect sensors are not as sensitive.

Those overshields also need grounded typically to the ECU otherwise that shielding which is basically a Faraday cage would build up static electricity to the point of high enough charge to discharge on the closest ground it can find. Helicopters for example buildup tremendous static electricity from the blades passing through the air. By grounding those shields to something they are in a constant state of discharging that charge instead of building it up. Shielded wires don't really carry any significant current, but they do need grounded to prevent static discharge spikes which can be hundreds of thousands of volts of electricity.

Very similar to old school "race spark plug wires" they were unshielded and would cause the interference heard through the radio.

[KGTM]

Pulse signals are very susceptible to interference. Any speed signal is a pulse based signal. Wheels sensors, driveshaft sensor, crank signal, cam sync, Wideband O2's even. Where the computer is processing VERY fine signal pulses at a very high rate outside noise making that signal dirty can cause issues. That's also why those wires are twisted pairs to keep the wire from causing noise from itself. The signal and feed being twisted cancels out the interference from itself. The worst offenders are magnetic pickup sensors as they read magnetic interference intentionally, and shielding reduces external magnetic interference. Modern Hall effect sensors are not as sensitive.

Those overshields also need grounded typically to the ECU otherwise that shielding which is basically a Faraday cage would build up static electricity to the point of high enough charge to discharge on the closest ground it can find. Helicopters for example buildup tremendous static electricity from the blades passing through the air. By grounding those shields to something they are in a constant state of discharging that charge instead of building it up. Shielded wires don't really carry any significant current, but they do need grounded to prevent static discharge spikes which can be hundreds of thousands of volts of electricity.

Very similar to old school "race spark plug wires" they were unshielded and would cause the interference heard through the radio.

For most part any twisted pair is intended to be differential like the can bus or wheel sensor cam position sensor which has a very low signal level and even them have no shield as the connectors on all the hub is not designed for ground wire, hall sensor generally have no need for shields they also have higher voltage so less need, even today most spark plug wires that I know 0f do not have shield, but has higher resistance than the old just straight wire and this limits the current and lower the ground noise generated by sparks and less possible audio noise.

Aslo one has to be careful about shield and its termination, when grounded on both end large ground current could flow and that is not always good and if a main ground is removed very large current can go through these and burned them up as they are not intended for large current flow.

Mostafa