DIY Wiring harness info

[Mark_17]

LXCams wiring mess on that chevy truck inspired me to ask here first.

I have a project car that I want to wire up on my own. I'm not interested in buying a wiring harness. I want to build it by myself and learn on my own. This is a long long term project and I'm OK with that.

Does anyone have any recommendations on where to go about learning how to do this? IE Books, websites, etc.. I have general wiring knowledge but would like to learn more.

My project car is a 1988 IrocZ Camaro. Its totally gutted.

I planned on using a Leash Wiring board with plenty of add ons for future mods.

This car is starting as strictly race, it will see no street time. All I will need to run is wiring for headlights, water pump, fans, and ignition. Motor will be carb'd with a mechanical fuel pump.

The plan is to buy a wiring board with enough add ons so in the future I can swap to EFI, electric fuel pump, power windows, turn signals, etc if I so choose.

 

[jsaw]

I would start with making up a schematic showing all of the circuits that you plan on using. then you will at least get an idea of how many circuits / wires you will need

 

[bigguns69]

https://www.waytekwire.com/?gclid=C..._d1OsxjJ5NqwcC2QLlZBnz_GAgO3MNhYaAuqREALw_wcB

https://www.womackmachine.com/education/textbooks/

Waytek is good source for components for wire harnesses. I have used Deutsch connectors for OEM construction and farm equipment for decades. You should be able to find what you need here then can price it out at other locations on the interweb.

Electronics is a lot like hydraulics. Current is flow, Voltage is pressure, Diodes are check valves, switches are like directional control valves, capacitors are accumulators, relays are electric switches, fuses are for safety, potentiometers are adjustable flow controls, resisters are static flow controls, etc.

Get good at reading and drawing up electrical schematics and learn the basic symbols.

You can lay out wire harnesses on a table or large plywood and rough in the end connection bare wires. Hold the bare ends with paper spring clamps screwed to the plywood. Label your wires and get a scheme going. Use black for main ground, green as local grounds, red for main power runs, orange for fused power runs, other colors for categories such as blue for front lights, yellow for tail lights. Label your wires and get comfortable with soldering and heat shrink tubing and finalizing harnesses with a sleeve of some nature.

It's a lot of fun and satisfaction. Let me know if you need anything else.

 

[rollinlower]

Wire it yourself lol

 

[Mark_17]

https://www.waytekwire.com/?gclid=C..._d1OsxjJ5NqwcC2QLlZBnz_GAgO3MNhYaAuqREALw_wcB

https://www.womackmachine.com/education/textbooks/

Waytek is good source for components for wire harnesses. I have used Deutsch connectors for OEM construction and farm equipment for decades. You should be able to find what you need here then can price it out at other locations on the interweb.

Electronics is a lot like hydraulics. Current is flow, Voltage is pressure, Diodes are check valves, switches are like directional control valves, capacitors are accumulators, relays are electric switches, fuses are for safety, potentiometers are adjustable flow controls, resisters are static flow controls, etc.

Get good at reading and drawing up electrical schematics and learn the basic symbols.

You can lay out wire harnesses on a table or large plywood and rough in the end connection bare wires. Hold the bare ends with paper spring clamps screwed to the plywood. Label your wires and get a scheme going. Use black for main ground, green as local grounds, red for main power runs, orange for fused power runs, other colors for categories such as blue for front lights, yellow for tail lights. Label your wires and get comfortable with soldering and heat shrink tubing and finalizing harnesses with a sleeve of some nature.

It's a lot of fun and satisfaction. Let me know if you need anything else.

This is perfect. Thanks for the info. I'll start here and let you know if I need anything else. Much appreciated.

Wire it yourself lol

That's the plan. I'm not sure what I'm missing?

 

[LXCam]

Mark, you've already gotten some good advice but I wanted to add something. Buying all the components but especially the wire is just not cost effective. As an individual you can't even buy just the wire for what you can purchase a generic pre-fabricated harness. Oh you can save quite a bit of coin buying spools of wire in 500ft rolls but the key to a clean set up is the correct gauge and dedicated colors. To do it right you could easily buy a hundred rolls when all is said and done. Or you could buy bulk in different gauges and two colors and go thru the hassle of identifying each one.

You'll learn a fair amount just buying a pre-made harness and fine tuning the lengths and installing the connectors.

 

[theoldwizard1]

This probably does not apply because your car is not going to see weather. Any one building a harness from scratch that WILL see weather should use "marine", pre-tinned wire. You will have less corrosion and it will last longer.

Personally, for ring/hook/spade terminals and **** splices, I like to use un-insulated connectors and marine/dual wall heat shrink. Or at least use insulated connectors that can be heat shrunk.

Many years ago I was involved with making several "add on" harness for prototype production cars. The big problem was "how long". Kind of wasteful, but we always made the harnesses 5' - 10' longer than it needed to be and left the connectors off of one end. This way, you had a lot of extra to play with when you installed it in your car. We would twist the bundles of wire instead of wrapping them (this works okay up to about 4 or 5 18 gauge wires). "Harness wrap" (1" wide electrical tape with no adhesive) looks better, bit it is difficult to find at reasonable prices.

Where you do need to use electrical tape, but the "good stuff". Scotch 88. The cheap stuff comes off when it gets above 90.

 

[ransil]

Having looked into this a few times, buy a harness, look at Ron Frances wire works, its all piece together, you get marked multi colored wires, pick the components you need.

Sent from my SM-G920V using Tapatalk

 

[rollinlower]

With mine I’m building a complete rewire I will have three of those boxes so I can power everything independently or in series the way I like all the electrical will be housed on this board except batteries of course lol


Sent from my iPhone using The Garage Journal mobile app

 

[2oolhound]

https://www.waytekwire.com/?gclid=C..._d1OsxjJ5NqwcC2QLlZBnz_GAgO3MNhYaAuqREALw_wcB

https://www.womackmachine.com/education/textbooks/

Waytek is good source for components for wire harnesses. I have used Deutsch connectors for OEM construction and farm equipment for decades. You should be able to find what you need here then can price it out at other locations on the interweb.

Electronics is a lot like hydraulics. Current is flow, Voltage is pressure, Diodes are check valves, switches are like directional control valves, capacitors are accumulators, relays are electric switches, fuses are for safety, potentiometers are adjustable flow controls, resisters are static flow controls, etc.

Get good at reading and drawing up electrical schematics and learn the basic symbols.

You can lay out wire harnesses on a table or large plywood and rough in the end connection bare wires. Hold the bare ends with paper spring clamps screwed to the plywood. Label your wires and get a scheme going. Use black for main ground, green as local grounds, red for main power runs, orange for fused power runs, other colors for categories such as blue for front lights, yellow for tail lights. Label your wires and get comfortable with soldering and heat shrink tubing and finalizing harnesses with a sleeve of some nature.

It's a lot of fun and satisfaction. Let me know if you need anything else.

Thanks for a GREAT POST! I've copied and pasted it to my files for future use

I've only rewired motorcycles which are a heck of a lot easier than a cage I had a large stock of coloured wire in many gauges and large quantities of different connectors etc. I was often worshiped by fellow bike riders with electrical problems back in the day.

With mc's I'd start with a schematic and a plan of where to mount the various hardware components and where to route the thickest part of the harness (you try to hide wiring on a mc). Then plan where the dis-connect junctions are so you can remove the wires with the component that you need to service in future. Now mount all hardware and components where they are going to be. From there I'd just start running wire, longest first, and taping it down leaving extra length at each end until every wire was run. Then start taping the harness tightly (which tends to shorten the wires you've run and why you don't solder the ends until done the taping). On a bike things like headlamp, right and left handle bar clusters etc. all have separate mini harnesses that disconnect from the main harness at junction boxes with simple push/pull barrel connectors (crimped and soldered). Hope mc wiring is not straying too far off topic.

 

[bdbecker]

I do agree with what LXCam posted, but if you do decide to DIY, label your wires and make good schematics for later reference. I used to do quite a bit of robotic fixture automation and its not always easy to remember how I did something a few years after I did a project. But I always thank myself for good documentation because when a problem occurs, I can go to my schematics and excel sheets (I also record part numbers, vendor info, and costs) and get the problem solved quickly.

You can buy a label maker and make custom tags, or you can buy booklets. This way you can a few colors in various gauges and still keep everything straight.

https://www.amazon.com/dp/B073YG3PX2/?tag=atomicindus08-20

Also, take the time to do the calculations and size your wiring appropriately.
http://circuitwizard.bluesea.com/

 

[Bigblue&Goldie]

Pay extra attention to wire chafing on sharp edges, and use proper sized fuses.......trust me.

 

[gte718p]

This probably does not apply because your car is not going to see weather. Any one building a harness from scratch that WILL see weather should use "marine", pre-tinned wire. You will have less corrosion and it will last longer.

Personally, for ring/hook/spade terminals and **** splices, I like to use un-insulated connectors and marine/dual wall heat shrink. Or at least use insulated connectors that can be heat shrunk.

Many years ago I was involved with making several "add on" harness for prototype production cars. The big problem was "how long". Kind of wasteful, but we always made the harnesses 5' - 10' longer than it needed to be and left the connectors off of one end. This way, you had a lot of extra to play with when you installed it in your car. We would twist the bundles of wire instead of wrapping them (this works okay up to about 4 or 5 18 gauge wires). "Harness wrap" (1" wide electrical tape with no adhesive) looks better, bit it is difficult to find at reasonable prices.

Where you do need to use electrical tape, but the "good stuff". Scotch 88. The cheap stuff comes off when it gets above 90.

I agree for the most part. I however hate electrical tape with a passion. I wire wrap all my harnesses. It is cheaper, and comes off clean if you need to change/fix something years later. It is something like 32-40 gauge wire so a little spool goes a long way.

 

[Fix Until Broke]

Having a good schematic and some sort of editing program is essential - It sounds like you're starting from scratch, but still have a plan before you buy anything. I'd start with the 1988 camaro full wiring schematic from the service manual, or a tool like ShopKey or Identifix, etc. I have a friend who has a subscription to ShopKey and Identifix so was able to make .pdf's and then edit them as necessary. Don't forget to get the connector details! They tell you part numbers for each terminal, wire seal, backshell, etc! Even if you're starting from scratch, this might be a good place to start unless you're really good at designing circuits. You can use the OEM circuit and strip out what you don't need/want.

I tried soldering connections (both manual and low temp heat shrink kind) and I prefer the crimp only with dual wall heat shrink after they're crimped. The solder wicks 20+ wire diameters up the wire and makes it much more likely to fatigue and break mechanically. The heat shrink crimp connectors have a built in strain relief of sorts that distributes any bending along the wire and minimizes the chance of fatigue breakage.

The Molex Permaseal have been very good
https://www.waytekwire.com/item/31980/Molex-19164-0044-Perma-Seal-****-Connector-/

Invest in a good crimper. I have one of these - not the whole kit, just the tool and a couple dies that I needed.
https://www.waytekwire.com/item/569/Waytek-569-Mobile-Crimping-Tool-Kit/

I really dislike tape most of the time - This braided split sleeving is awesome. It's expensive and I had to see someone else use it before I tried it, but it's totally worth the money. If you ever have to go back in a harness it's super easy, it looks very clean and is surprisingly tough against abrasion.
https://www.waytekwire.com/item/20341L/Braided-Split-Sleeving/

Labels are another thing to invest in - Especially on a long project. These are also a bit pricey, but last a long time. Get the marker for them - it's not a regular sharpie.
https://www.amazon.com/gp/product/B009DHQERE/?tag=atomicindus08-20

I kept the full wire harness from both the original and donor vehicle and was able to use that as the source for 90% of my wire. If you need to purchase wire, get a good quality cross linked insulation. "Primary" wire is just cheap junk vinyl and will break down with heat, cold, abrasion, etc. It's not worth the price difference to get the cheap stuff.
https://www.waytekwire.com/products/1454/Automotive-Cross-Link-Wire/

I always try to make as few splices as possible - If I needed to run another 2 feet of wire to get to the headlight or fuse block, I'd do that instead of a splice. This requires investing in the specific terminals, wire seals, etc so the connections are weather tite, but every splice is another chance for something to go wrong. If you're working with an 80's GM vehicle, most everything will be Metri Pack 150 or 280 series.
https://www.waytekwire.com/products/19/Metri-Pack-Connectors/

There are a lot of power distribution products on the market now that didn't exist to the average consumer just a few years ago. Most of these use Metri Pack 280 series terminals which fit all the ATM fuses and relays so that makes things easy. You can buy pre-configured ones for big $$ or empty ones for <$20. I got the empty ones and assembled my own as/where necessary.
https://www.waytekwire.com/products/1369/Power-Distribution-Modules/
These in particular use the same MP280 terminals so are very easy.
https://www.waytekwire.com/products/1369/Power-Distribution-Modules/&mfg=27

If this looks like I'm trying to get a sponsorship for Waytek, it's not - just a convenient place to get links quickly. All these items are available from DigiKey, Mouser, Allied, Del City, etc. Octopart is a great sourcing website for anything like this as well.

I wired a 2012 Duramax into a 1996 Buick Roadmaster Wagon and made everything work (ie, when you open the right rear door on the wagon, the 2012 dash says "Right Rear Door Ajar", automatic headlights, HVAC, etc). It felt impossible at times, but just work through it one circuit at a time and document everything you do on the schematic.

Hope this helps - Glad to help out if you have any problems or questions.

Good for you wanting to do it yourself and learn - Built not bought!

 

[theundermount]

wow very informative fix that was an very informative post !

 

[Ohmthis]

Most wiring projects be it automotive, residential, or our shops are made and broken in the planning stage. Besides planning for the present, you need to plan for the future too. I’m also on board with Cam on using an after market fuse box and basic wiring harness. You can then get the bulk of your project covered. Then by using a module or a fuse/relay box like below you can add what you need want at a later date.
https://www.amazon.com/gp/aw/d/B07MR64XK1?psc=1&ref=ppx_pop_mob_b_pd_title
I plan to use an after market harness for the truck I have to wire the basic items (lights, horn, ignition, etc) and then a box like above to add the needed power for stand alone EFI on the engine/fuel pump/electric fan/ etc. Hop this helps!

 

[Hagatronics]

Go to High Performance Academy and buy their online wiring course http://hpacademy.com
You'll be building looms for Formula 1.by the end. Very detailed info from how to ground, what gauge cable.and how to terminate connectors

 

[Mark_17]

Wow, thank you everyone for all of the great advice.

This is a long term project that I am determined to build as much as possible myself. I'll do plenty of homework on wiring and then decide if I still want to build my own harness.

An example of the Leash board I am considering- https://www.leashelectronics.com/Pro-Street-Wiring-Board-PS2015.htm

 

[Hagatronics]

Here is an extract of the HP Academy wiring course. It's good info and worth the.$$

 

[Stooge]

Im not one to try and dissuade someone from a big learning project, but if you are buying that terminal block/ relayed input board for $200, you would be miles ahead cost wise buying a universal non-terminal ended harness with fuse panel for not much more money, and without having to chase down the dozens of possible specialty connectors, separate colored lengths of wire, etc that will nickel and dime you to death. You still have to make all of your own connections, figure out what you want to use, route it, etc but just saves having to buy it all separately.

 

[Hagatronics]

Im not one to try and dissuade someone from a big learning project, but if you are buying that terminal block/ relayed input board for $200, you would be miles ahead cost wise buying a universal non-terminal ended harness with fuse panel for not much more money, and without having to chase down the dozens of possible specialty connectors, separate colored lengths of wire, etc that will nickel and dime you to death. You still have to make all of your own connections, figure out what you want to use, route it, etc but just saves having to buy it all separately.

What is this? Can you share a link / pic as.an example?

 

[Fix Until Broke]

Wow, thank you everyone for all of the great advice.

This is a long term project that I am determined to build as much as possible myself. I'll do plenty of homework on wiring and then decide if I still want to build my own harness.

An example of the Leash board I am considering- https://www.leashelectronics.com/Pro-Street-Wiring-Board-PS2015.htm

That Leash board looks well built and there is a nice convenience factor there too (a lot of other nice things on their website as well). However as some others have mentioned, you're paying for the convenience. You can assemble a very similar/same thing for ~$60 in materials.

The littlefuse 60 position distribution modules ($17.16 each), the same Song Chuan relays ($3.57 each) and 100 terminals ($11.74) so for about $60 you can have up to 8 relays, more fuses than you'd ever need and the knowledge/satisfaction of doing it yourself. If you screw something up, worst case you're out a relay, fuse or have to crimp another wire (the terminals are removable from/reusable in the block, but once crimped on the wire they're permanent)

I used two sets of the above - have 8 relays in each one. One module is switched to power, the other module is switched to ground. I can pull in 1, 2, 3, etc relays with one signal or have them run independently, some have common power, some have separate power, etc. For the higher amp draw circuits, I ran 2 relays in parallel so there's some redundancy built in. Very flexible.

Again, the Leash products look nice, but you'll have to determine if they're worth the money/convenience vs doing it yourself as mentioned earlier in this thread.

 

[Mark_17]

That Leash board looks well built and there is a nice convenience factor there too (a lot of other nice things on their website as well). However as some others have mentioned, you're paying for the convenience. You can assemble a very similar/same thing for ~$60 in materials.

The littlefuse 60 position distribution modules ($17.16 each), the same Song Chuan relays ($3.57 each) and 100 terminals ($11.74) so for about $60 you can have up to 8 relays, more fuses than you'd ever need and the knowledge/satisfaction of doing it yourself. If you screw something up, worst case you're out a relay, fuse or have to crimp another wire (the terminals are removable from/reusable in the block, but once crimped on the wire they're permanent)

I used two sets of the above - have 8 relays in each one. One module is switched to power, the other module is switched to ground. I can pull in 1, 2, 3, etc relays with one signal or have them run independently, some have common power, some have separate power, etc. For the higher amp draw circuits, I ran 2 relays in parallel so there's some redundancy built in. Very flexible.


Again, the Leash products look nice, but you'll have to determine if they're worth the money/convenience vs doing it yourself as mentioned earlier in this thread.

Again, great info and much appreciated! I'm not committed to anything right now, so I'll absolutely look into this as well

 

[Hagatronics]

So the other approach is to use a Power Distribution Module (PDM). Not cheap but for a serious race car is absolutely unbeatable.

Wiring is dead simple, very reliable and can be programmed to do all sorts of cool stuff. E.g. if current of a pump exceeds a tolerance send a message to the dashboard and cycle power on the pump to reset it; or if a breaker trips then automatically reset it but only try three times.

Given you said you are going mechanical pumps and carburetors it's probably not your style. But worth considering if you are learning about different approaches to building a race car wiring loom.

I have a late model race car and needed to add half a dozen fuses and relays (coolant pumps for water to air intercooler, additional fuel pumps, oil.cooler pumps etc) and did it with relays etc. I really regretted not using a PDM.

Motec would be my goto but there are other cheaper brands

https://www.motec.com.au/pdm-current/pdm-directory/

 

[mikepelchy]

'm in the process of putting a 5.3 in my IH pickup. I figured out where I wanted to mount the fuse panel and how many fuse/relays I needed and then I went out to the junkyard and found one that fit my needs, and took a bunch of the harness with it. I thought it was a good deal for $20.

The bussman fuse blocks are pretty nice and relatively inexpensive but I do believe that the common bus bar they use is only rated for something like 80amps, so when you factor in electric fans, blower in the cab and headlights, that could easily be exceeded, requiring multiple fuse blocks.

 

[K13]

What is this? Can you share a link / pic as.an example?

There a tons of them out there. These guys will even configure to your own specs. I have a buddy that just had them build him a harness modified for his needs for $215.00.

http://rebelwire.com/rebel-wire-products.php?cat=Wire Kits

 

[bfdladder10]

Heres a site to get wire and fuse panels. I plan on ordering wire from them when im ready to wire my hotrod..

https://www.racersrods.com/

 

[Natemx]

Here is a link with a lot of information:

https://www.rbracing-rsr.com/wiring_ecu.html

 

[WaterBoyz]

Google "LS wiring harness".
There is no shortage of people who do harnesses.

Look at this guy's site. He pretty much is where everyone goes to.
http://lt1swap.com/wiringharness.htm

 

[Fix Until Broke]

Here is a link with a lot of information:

https://www.rbracing-rsr.com/wiring_ecu.html

There's some really good info in there - glad I saw that AFTER my wiring project is done (otherwise I'd still be at it!).

 

[ericlar80]

A lot of what you need to know if you want to make a project out of it:
https://www.rbracing-rsr.com/wiring_ecu.html

 

[Bad Mojo]

A lot of what you need to know if you want to make a project out of it:
https://www.rbracing-rsr.com/wiring_ecu.html

Thanks for the link. I am looking forward to reading it all.

 

[ericlar80]

Thanks for the link. I am looking forward to reading it all.

Just note that it is over the top for most applications, but interesting nonetheless.

 

[Bad Mojo]

Just note that it is over the top for most applications, but interesting nonetheless.

Absolutely, it is also incredible to see the skill and craftsmanship when it needs to be done well.

 

[RWorth]

Mark, speedway has some nice setups for track cars like these.

https://www.speedwaymotors.com/Keep-It-Clean-Switch-Panel,49548.html

And if you only have a few items to run you can buy a very small atc fuse block with 4 to 10 fuses. Your system will be so simple it will be easy to design and build, if you want tell me what you want to run and I'll draw a diagram and give you a parts list. I've been collection sources for building the system for my 66 f100 so I have a pretty good list.

 

[paranoid56]

Go to High Performance Academy and buy their online wiring course (hpacsdemy.com).
You'll be building looms for Formula 1.by the end. Very detailed info from how to ground, what gauge cable.and how to terminate connectors

i paid for one of theirs and it was great. need to do buy the other one next.

 

[Ohmthis]

Mark, speedway has some nice setups for track cars like these.

https://www.speedwaymotors.com/Keep-It-Clean-Switch-Panel,49548.html

And if you only have a few items to run you can buy a very small atc fuse block with 4 to 10 fuses. Your system will be so simple it will be easy to design and build, if you want tell me what you want to run and I'll draw a diagram and give you a parts list. I've been collection sources for building the system for my 66 f100 so I have a pretty good list.

I’m curious as to your setup. I too have a 66 f100 that needs a total rewire. My plan was to use an aftermarket harness and add relays as necessary.

 

[WaterBoyz]

Go to High Performance Academy and buy their online wiring course (hpacsdemy.com).
You'll be building looms for Formula 1.by the end. Very detailed info from how to ground, what gauge cable.and how to terminate connectors

Should be...........

https://www.hpacademy.com/

 

[59 wagon man]

I have completely rewired 2 cars and one of those twice. there is a basic simple book called how to wire a hot rod from start to finish. it runs about $10 and was very helpful with its simple to understand drawings

 

[kerrynzl]

I have a project car that I want to wire up on my own. I'm not interested in buying a wiring harness. I want to build it by myself and learn on my own. This is a long long term project and I'm OK with that.

My project car is a 1988 IrocZ Camaro. Its totally gutted.

.

Hi Mark, Do you have the original harness still???

I built a "production class" racer from a 3rd gen back in 2004. [Weight was everything]
With an HEI things are simple
But my advice is to pull the original harness out, Label all the plugs and connectionsas well as the fuse box etc.
Then lay the harness out on the garage floor and Unwrap it. While unwrapping it ,use zip ties every 6" or so to keep it together.

Then start pulling out and removing unnecessary wires along with unnecessary components [heater, rear wiper, demister, door lights etc]
As you pull wires keep tightening the zip ties

This will surprise you when you fill up a 10 gal bucket with all the ****.

I threw the fuse box away and used a circuit breaker board.All the gauges were mechanical except the Tacho.
And I also mounted the battery in the rear with a master kill switch.

The problem with making a new harness is all the Bullet and Spade connectors are exclusive to GM and expensive.

I got my Camaro down to 2800lbs and it was still legal on our roads in NZ with full Upholstery except 2 front race seats
Every single washer or unnecessary bracket/component was removed

And one last thing, this is not a game for colour blind people

edit:
Get 2 large photocopies of your wiring diagram and some kids water colour "sharpies"
and start colouring the wires [as close to factory colours as possible]
On the 2nd photocopy get a correction pen and start removing unnecessary circuits and it will suddenly start looking simple.