Re-Wire Your Whole Damn Car - How To Do It Correctly & Inexpensively

sometimes we all just want to start over and never more so than when you're wiring a car if you have an old car or are turning a car into a race car a lot of times it'll be easier in the long run just to rip it all out and start over this seems really daunting especially when you look at the random wad of colored wires running all over the car but it's actually easier than it looks and i'm gonna go through it all right now [Applause] newer car electronics are super complicated there are controllers all over and miles of wire makes you long for the old days when things were simpler but the old days were also a rat's nest of outdated sometimes with actual rat's nests rewiring your car seems like it's much more difficult than it is it's actually pretty straightforward unless you have a new car like a tesla or something if your car has a body controller rewiring is probably outside of the scope of this video what we're talking about here is your older cars like 90s and back or if you're building a race car or an off-road only vehicle or a motorcycle we're going to go through the process here we're going to talk about the different circuits how to plan out your wiring what specific parts to buy with what part numbers what type of wire to use how to protect your wires and what to do when it doesn't work a quick glance at a car wiring harness makes the prospect of rewiring seem super daunting but it's not that difficult because most of the circuits on a car are discreet they're separate and they don't interact with each other they seem like they do because they all go to the fuse block and they all run through big connectors but you don't really have to wire the whole car to get the headlights to work you just have to wire the headlights so wire the headlights then move on to the next thing do that seven or eight times and you're done the engine control unit will often have more wires than the rest of the car combined that's certainly the case on my car i recommend thinking about the ecu wiring as kind of a separate thing if you're doing a race car or something with a standalone engine management computer you'll usually be able to buy a wiring harness specific to your application next week i'm going to talk about wiring up a specific ecu the megasquirt and that'll be helpful if you have specific ecu wiring questions even if it's not specifically with the megasquirt if you follow my videos you know that i like to do things inexpensively but i also like to do them correctly there are a lot of off-the-shelf solutions to rewire your car but most of them don't fall into the inexpensive category there's also a lot of cheap solutions that don't use the right wires and don't have the protection from the environment that you really need it's also easy to go overboard and spend too much time as usual what we're looking for here is the optimization of laziness cheapness without sacrificing quality the holy trifecta the off-the-shelf wiring solutions are not terrible if you want to spend the money but they do have some drawbacks cars are always different different circuits different switches the off-the-shelf kits are probably not going to have the right fuses and wires and relays you'll always end up with extra or not enough and you still have to plan out your system you still have to cramp the wires to the connectors loom it run it all around the car get the right grounds and switches a lot of times these kits don't make the hard part easier they make the easy part easier for more money and you still don't get exactly what you need if you do get the pre-populated wiring kit get one that is for sure bigger than you need you can use a removal tool or a screwdriver to pull out the wires you don't need and set them aside for later if you're doing it from scratch good for you later on i'll give you the exact part numbers you need so that it will be in fact painless [Music] regardless of your chosen path you still need to plan the system out the first thing we want to do is bust out the crayons and draw our wiring diagram again this is easier than it looks this mess you see here is my wiring diagram and i know it looks like a disaster at first glance but i promise it makes sense and it makes wiring the car so much easier first write down everything in your car that needs power horn tail lights ecu everything for each thing figure out what size fuse you need and if you need a relay the fuse size can be figured out by checking the old fuse block or just do some googling if you're not sure err on the side of too much fuse it doesn't need to be perfect but once you have a good idea of all your circuits it's time to start drawing i used keynote and i recommend that or powerpoint or really anything that will let you draw and easily modify colored lines and boxes it's important that it can be easily modified because you will modify it several times everything needs at least two wires a power and a ground usually there's a switch in there to turn it on and off all your power wires will come from the same place the fuse block your grounds will come from either the battery negative terminal a grounding strip or sometimes just the body or engine block so let's start with the main switch the key or switch or whatever turns the car on i run everything through one main relay this is a 40 amp relay which is more than enough for this car i like this relay because it's waterproof and i can stick it under the hood next to the battery you can get bigger automotive relays they sell 100 amp relays like this one and of course you can get a fat chunker like this to flow lots of current you can also separate the high amperage stuff out to its own relay this is a good idea for light bars or anything pulling lots of current you can wire that relay up so that it gets its power from the battery but the switch side comes from the main relay i'm not going to do that though because i like simplicity and running everything through one relay is super simple so the main switch turns on the main relay which allows electricity to flow to the fuse block now all the fuses have power our fuse block also has some relays in it the relays also get their power from the main relay quick side note most of you probably know what a relay does but if you don't that's okay we're all here to learn a relay is a switch that's activated by electricity you might be asking if we have a main switch why don't we just run all the electricity through that switch well a lot of switches can't handle the amount of current we need i said this relay can handle 40 amps well this switch can't so i use the switch to turn on the relay which only takes less than one amp then all the 40 amps goes through the relay this is especially important with things like engine control computers the computer can send a signal out that says turn on the fuel pump or run the cooling fan but you don't want 20 amps running through your ecu because it has a lot of sensitive electronics measuring small changes in voltage so you have it trigger a relay sometimes you'll see a relay with a diode or a resistor built in this is there to protect those sensitive electronics that are turning them on you'll sometimes get a brief voltage spike when the relay turns off and the magnetic field collapses the relay and diode prevent that spike from damaging the electronics the diode works better but it only works in one direction so you have to make sure to wire it up correctly there are some things that you always want to have power the only things on this car that i want to always have power are the horn and the dash everything else requires the key to be on the dash has an always-on input to keep the clock running since it's just those two things i'm just going to use one of these in-line fuses right off the battery if you have more than a couple of things that need 12 volts all the time you might consider a small standalone fuse block this is my horn circuit i have a wire from the battery to my inline fuse and then it splits off one to the dash and another wire to the horn button then a wire from the button to the horn the horn is grounded off the body which we'll talk about later after that we wire up the headlights that switch has outputs for high beam low beam as well as tail lights and the front running lights your switch should be able to route the electrons as needed i use a toggle switch in my car it uses the high beams when you switch it up and the low beams when you switch it down i used a dual pole switch so that turns on the tail lights in either the high or low beams a dual pole switch is basically just two switches in one i'm using a brake pressure switch that needs a relay but a lot of time you can just run your lights through the switch that's activated by the brake lever this is a simple brake light circuit if your brake lights are also your rear turn signals then the wire coming from your brake relay will actually go to the turn signal stock the signal stock will send the brake light power through unless you've moved your signal switch then it will send the signal relay power to the flashing light and the brake relay power to the other brake light here's my starter circuit the starter solenoid gets its switch side power from the fuse block so that you can't turn on the starter when the key is off the ground for the starter solenoid comes from either the clutch switch or the neutral switch this is a safety to make sure that you can't start the car unless it's either in neutral or the clutch is pressed i added a diode so that my neutral light on the dash doesn't go on every time i press the clutch basically a diode is kind of like a one-way valve for electricity all of this other stuff is my ecu wiring again it's mostly discrete stuff some of the sensor wires will share a ground but you can mostly wire things up one thing at a time i'm going to skip over the specific ecu wiring because it's always so different because i'm going to talk about that next week there will be a link to that video in the description when it's available you need to buy some stuff for this project but not much i'll talk about the specifics on these things later and the part numbers are all in the description first you'll need a fuse and relay block this will also need crimp connectors and rubber boots you'll also need a crimper and you can use the 10 crimper but if you're looking for an excuse to buy some nice tools and i know you are go spend 100 on this guy you'll need wires of course and again i'll talk about that later you'll need labels and trust me when i say you need them future you will appreciate it a lot you can write on tape and wrap that around but it's nicer to use a label maker if you're going to get the label maker and get one that prints on heat shrink this will really up your professionalism you'll also need regular heat shrink to put over the connectors i have two sizes eighth inch and quarter inch both with a three to one shrink ratio this solves almost all my heat shrink needs so much so that i bought giant spools of both of them although this is probably overkill for one car rewiring you also need to shrink the heat shrink so you'll need a heat gun or just use a crack lighter like i do is this a crack lighter or a meth lighter are they the same thing perhaps some things are better left unknown either way maybe right next to your fuel rail is not such a good place you'll probably also need a pin removal tool i got a bunch of random pin removal tools and it's not the best but it does the job a multimeter will help a lot but you don't need a good one basically we're just going to use it to see if a wire has 12 volts or zero volts or whether something has infinite resistance or near zero resistance you'll also need fuses relays a grounding strip and just loads of zip ties [Music] you need a specific kind and size of wire you wrote down the fuses you need for each circuit right no you skip that part well you should do it now because that will inform what size wire you need if you know your fuse size and you know about how long your wire is going to be you can look up the wire size you need on this chart you don't need to get the exact size shown but it does need to be at least that big if your system is like mine you probably only need a couple of sizes maybe 18 gauge and 12 gauge also you don't need all different colors car manufacturers use all different colors for reasons that are not entirely applicable to us i'm using eight red black white gray yellow blue green and something else there are some others from the wiring harness that came with my ecu i use yellow for the right side turn signals but i also use them for the coils and the headlights i'm not going to confuse these three things the switches and components are all in completely different places for everything that's always grounded i always use black wire personal preference but it simplifies things i label all my wires so it's not a problem labeling is better than different colors anyway because you don't have to look up what green with red stripe is you just read the label the type of wire you buy is important because your car is a pretty harsh environment you don't want to just run speaker wire to your fuel pump you'll need temperature and abrasion resistance as well as resistance to oil and other chemicals the stuff you find in packages at your local hardware store is probably not the right wire gpt is a basic general purpose automotive wire it doesn't have great abrasion or temperature resistance sxl is better it has a cross-linked polyethylene jacket which means something but it has better resistance to heat and abrasion gxl and txl also have this insulation but it's thinner so it fits in tighter spaces it's not something i've had a problem with if you need a bigger hole for wires than just drill a bigger hole sxl is a good bet there are places online where you can buy 25 feet of eight different colors of this stuff for not too much money also you can just buy that package crap at the hardware store that's mostly what i did but you need to loom it correctly which we'll talk about later wiring gets messy quick so be sure and take a moment from time to time to clean up or don't whatever i'm not your dad for the fuse and relay block i recommend this it's made by bustman it's made well and it's 22. they have different sizes so you can get the size you need i'm using this one that has 10 fuses and 5 relays because my system is pretty simple if you have more circuits and you need more fuses and relays you can get the series 15400 which has space for i think 10 relays and 40 fuses they also sell blocks like this which are compatible with any 280 series components here's the cool thing about these the spacing on these is same for 280 relays and mini fuses diodes shunts blades circuit breakers you can set it up however you want with these components they're pretty cool but i'm going to stick with a bustman that has the 5 relays and 10 fuses because that's what i need if i needed more than five relays or ten fuses i would probably just get two of the smaller ones one of them for the engine and one for everything else they sell these with or without a bus bar connecting one side of all the fuses or the switching side of all the relays you probably don't want that because some of your relays might need to be switched with 12 volts instead of ground and some of your fuses might need a switched input i recommend getting this one if you are getting two of these one for the engine and one for the car you can probably get one of them with the bus bar just plan it out people love this fuse block but frustratingly a lot of reviews say this is awesome if you know what pins to use but then they don't tell you which pins thanks for nothing these are the pins you need get the right size for your wire i just used one size for everything it's probably fine also get the little rubber condoms so we can practice safe wiring these fuse blocks all use any 280 part including the 280 micro relays which are a little bit different from the cube ones you normally see they're super common in oem cars picker seems like a good brand they sell one with a diode that's good for the relays connected to the ecu these relays mostly cap out at 35 amps but they do sell this fatty here that goes up to 50 amps and takes up three slots i get my fuses from little fuse or bustman [Music] you need a good ground bar a place to get a good ground to all your random electronics i had to make a bracket to hold my fuse box so i'm just going to tap some holes and add studs then when i bolt it into the body i'll run a fat ground line from the battery to one of the bolts holding it in so then it'll have a good ground and the body will have a good ground so i can just run a ground wire to the body for things that are away from the ground bar like the horn and the tail lights if you do that make sure to check the resistance between the negative battery terminal and the place on the body that you have the ground attachment it should be very close to zero for the headlights fuel pump and anything that's pulling more than a few amps i'll usually just run a ground wire back to the ground block just to be sure the ecu ground should almost always run directly to the battery negative take a moment here to clean up your mess didn't we just do this [Music] [Applause] [Music] do not get these connectors you never get a good crimp on them because it's just kind of squished plus these insulation pieces never stay on after you crimp the non-insulated kind get a good dent in the back that holds the wire tight use non-insulated and then put heat shrink over it by the way the little dent goes in the back opposite of the split same thing with a splice use naked ones and heat shrink ask five people how to connect two wires and you'll get five different answers and lots of ways that you should absolutely not do it there will definitely be a discussion on this topic in the comments but this is my preferred way to do it and the preferred way of most of the good electrical technicians that i've worked with who are you going to believe some on the internet or this on the internet in any case if you use wire nuts to connect wires in your car i will come to your house in the middle of the night and slap the out of you quick side note while you're wiring everything up swap out your main fuse for a 5 or maybe 10 amp fuse and then check your circuits as you go that way if you have some problem down the line you won't risk burning up your wires once everything is wired and works individually you can swap back in your 40 amp or whatever size fuse you're using try not to over connect through things i sort of err on the side of not using connectors and then if i find myself needing to cut a wire to remove something i'll add a connector then if you're going to the racetrack where you might need to swap out things fast put some thought into how you're going to remove things like the fuel pump but connectors are failure points so be careful we once lost a race that we spent an entire year preparing for because we had a cheap connector fail on us so maybe i'm hypersensitive to bad connectors i prefer these delphi connectors i think delphi changed their name to aptiv but i'm gonna call them delphi because that's what i've always called them i'm old and i don't like change the quality to cost ratio is great these things are about two or three dollars a connector once you get the pieces you do have to buy them in pieces but you already bought a crimper so you're good to go the part numbers are listed here and in the description with links to way tech in fact in the description is a google drive link that has all of the part numbers and all of the links so that all you have to do is just click on the links and add them to your cart so impossibly easy you need to protect your wires there are a few different ways to do this a common solution is to use this flexible black plastic stuff i call it gutter tube because it looks like it should be rounded drainage down a hillside i don't like it but in its defense it is pretty good at protecting the wires and it's easy to add wires afterwards this is my preferred wire protection it's just a woven plastic that's expandable sort of like a chinese finger trap i got one size 3 8 of an inch and i used it all over the car to use it just cut it to length burn both ends with your crack lighter to keep it from fraying and slip it over the wires if you're careful you can poke a wire through the side and have it come out in the middle the drawback of this stuff is that you can't really put it in once you've plugged in your wires you need to plan ahead fortunately we did that already there are places where it doesn't make sense because you have lots of wires coming out of a short section like the fuel injectors there i use fabric tape my favorite tape for this is the fabric tessa tape it looks good and has good abrasion resistance tessa makes a good electrical tape too the electrical technicians at tesla used this tape on the prototypes back when i worked there so the tesla techs tested the teslas with tessa tape tessa tape was used on the teslas that were tested by the tesla techs you'll want to get zip ties to secure the ends and also to secure your wire routing around the car two pieces of advice with zip ties don't buy the cheap ones and buy them by the thousand if you're anything like me you will use all thousands of them before your milk expires you really only need two sizes i have 12 inch and three inch okay but seriously how does this table keep getting this messy [Music] when i had my stuff all wired up i sat in the car flipped the main switch and nothing happened you might have a similar issue if you two forget to put in the fuses you need fuses if one of your circuits isn't working just remember that everything is in a loop usually it goes battery and then fuse relay or switch component and then back to battery check the voltage at each one of those locations and you'll figure out where your problem is also check continuity by measuring the resistance between those points that'll tell you if anything is wrong between them or if you forgot to run a wire or something i recommend putting in one fuse and relay at a time and testing each thing individually remember this is mostly discreet stuff so you can track down problems pretty easily that's it your car is wired and that took what 18 minutes amazing i'm not really sure what other questionable ideas i'm gonna have for my cars in the future but i can guarantee i will have them so hit that subscribe button and find out thanks for watching

Channel: SuperfastMatt

Views: 14,631

Rating: 4.9778271 out of 5

Keywords: wire a car, car wiring, motorcycle wiring

Id: pSXv8RHa22I

Length: 19min 9sec (1149 seconds)

Published: Tue Jan 19 2021