Upgrade Engine In Corolla

its a lot of work and trouble. not sure if its worth the few extra horses. i would swap in the 2zz-ge. requires extensive wiring.

Engine Swap Wiring Secrets REVEALED! Written by Dr Tweak

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Keep in mind that this is not a step by step guide to wiring a 3SGTE swap, but is a general guide to wiring ANY Toyota swap. Also, yes, I am willing to help people out over email with wiring problems, but I'm not going to tell you step by step how to do it. You need to figure that out. If you would like to leave the wiring headaches to someone else, then you can send the wiring harnesses to me and I will do it for you, save for a couple wires that usually need to be wired directly to the car. The rates are usually pretty cheap too, depending on what you want done.

Basically, there are three methods of engine swap wiring:

1. Modify the COMPLETE donor car (new engine) wiring harness to fit your car

2. Modify the COMPLETE stock car (old engine) wiring harness to fit the new engine

3. Take half of one harness and half of the other and put them together (most common option)

Now, before we get too far, let me explain a few terms. First of all, the "engine harness" is the thick bundle of wires that goes from your fuse box and engine in though your firewall and to the ECU and other plugs in the car. The "engine harness" includes MANY wires that have NOTHING to do with the engine. The "engine harness" is in fact, two parts. Many people refer to the part that has to do with the engine as the "engine harness", and the other part (which is a lot of car related stuff) as the "body harness". Technically, this term is not correct as the "body harness" is the harness that goes all around your car and does all the switches and rear lights and so on. Keep that in mind.

Also when I use the term "donor harness" I mean the one going to the new engine that you're putting in. When I say "stock harness" I mean the one going to your old engine.

The term "dash harness" refers the the harness behind the dash. The "engine harness" plugs into the "dash harness" in several places, with most swaps.

I will briefly touch on the first two options. The first method can be used in cases where the two harness are very similar. For example, if you are swapping a a 2ZZGE into a car that had a 1ZZFE, you could do it. The tricky part is, you need the COMPLETE wiring diagrams from BOTH cars. Since most JDM engines we swap only have the engine wiring diagrams available, this option isn't feasible. It is an option if the donor engine is USDM and you can get the original car diagrams. Basically, you will using the entire donor harness and running the wires for the car related stuff to the original plugs for you car.

By the way, if you ever need any diagrams from any USDM car, just email me and I can get them for you for around $20.

Now, second option. This option can be used when the new engine and the old engine are quite similar in how they are controlled. For example, you can use a stock 3EE engine harness to run a 4EFTE. However, several changes will need to be made to the 3EE harness. Basically, you will take the stock engine harness and make it into a harness for the new engine. You will need to swap over some plugs, add a couple wires, and change some wiring around.

Then we have the third option. This is the most simple, most common, and in my opinion the cleanest way to swap. It is sometimes more work than the above options but gives less trouble in my opinion. So here is how you do it:

First, remove the stock engine. Then sit the two engines (new and old) next to each other. I like to do my harnesses still attached to the engines. Most of the time you don't have to totally disconnect them. Now, remember how I said the engine harness is really two different parts? Here's how it goes:

The first part is the *engine related* wiring. This is everything between the ECU and the engine itself. This is the easiest part. You DO NOT, at any time, cut, alter, or in any way molest this wiring on the donor engine!

The second part is the *body related* wiring. This is everything between the dash harness (where it plugs into the engine harness) and the fuse box, and some things on the engine. This part is a little tricky. Sometimes, if the engine has come from the same model car as yours, the body related wiring is almost exactly the same. Other times it is incredibly different! This is where you can decide if you want to use option 1 or 2 (if the harness is very similar). Keep in mind, NOTHING in this part of the harness is on the engine wiring diagrams! So that 20v silvertop diagram that you got is NOT going to help you here at all. On the other hand, if it came from a USDM car, you can get the complete diagrams and figure out what the wires do. Then you just need to swap the plugs at the fuse box and the dash harness. That's option 1.

Now, with lots of engines, and the 3SGTE is one, there is a third plug on the ECU that goes directly from the ECU into the dash harness. Normally these plugs are very similar between the old and new engines. However, on some swaps the old (or new) engine doesn't have this plug! This is where you need the engine wiring diagrams. Figure out what each of the wires goes to, and there should be a corresponding wire on the other harness.

Okay let's move on. So you already know about the third plug, that's easy, there are usually one or two other ECU plugs, and you know not to touch any of those wires on the donor engine harness. However, on the stock engine harness, the wiring is not needed and can be cut right out if you need to.

Here's what you're going to do. Starting at the ECU/dash plugs end, strip off the looming. Be careful not to cut any wires as you do so. You will notice that with many engines there is a kind of 4-way intersection of wiring right on top of the tranny. One part goes up into the engine, one goes to the firewall (ECU and other plugs) one goes to the fusebox, and the other might go off to AFM and that kind of thing or maybe the tranny. Now listen, the wiring that goes up into the engine towards the injectors and whatnot does NOT need to be unloomed on either engine, MOST of the time.

So, unloom all of the wiring from the ECU plugs and dash harness plugs right down to the 4-way or 3-way intersection, and keep going towards the fuse box plugs.

Now, I like to do this a little at a time on each engine harness, working back and forth, but you can do it with one at a time if you wish. With the stock harness from your OLD engine, you carefully trace all the wiring from you dash plugs, that is your *body related* wiring, down into the fusebox and whereever else it might go (sometimes the windshield wiper wires are in there, etc). Remove this part of the wiring from the harness.

Now pay attention: the body related wiring and the engine related wiring DO interface in several places. The biggest ones to keep in mind are the starter circut and the charging system. This is when it's handy to have the stating and charging system diagrams on hand. Normally, these systems are very similar, and you can usually use either one. Just take note of where the wiring interfaces and cut those wires, always labelling what they went to. This is why I like to do both harnesses side by side, so that I can compare them.

Keep in mind this whole time, the body related wiring that you are pulling from your stock engine harness is going BACK into your car. So take care of it. You should end up with a bunch of wires going from your fuse box to your dash harness, and a few wires cut that went to the engine. (Some of these wires will be a/c related items, oil pressure and water temp for your guages, and so on.)

Now move over to the donor engine harness. Remeber all the body related wiring that you pulled from the other harness? You're going to do the same thing here, the difference being that you want to keep the *engine related* wiring intact, so be careful with it. The body related stuff can be cut as you need to and remove it from the harness.

Then, take your body related wiring from the stock engine harness and place it next to the engine related wiring from the donor engine harness. See what's going on here? You're taking half of one harness and half of the other and making one NEW harness! Just remember, you want ALL the engine related wiring from the NEW engine, and ALL the body related wiring from the OLD engine harness.

Now you need to integrate the two. If you did a good job when taking them apart and labelled any wires you cut, you will basically be able to match them up! However, all harnesses have some differences. Sometimes, you will just leave some wires hanging that you didn't need. So don't panic if you get done and there's no home for some wiring, some of it is not needed. Also remember your wiring diagrams. They will be essential during this entire process.

Once the connections have been made, you will be all set. It should basically be plug and play. Now I will go over a couple of technical items.

Items that you need: Knife, multi-meter, wire cutters, soldering iron, solder, flux paste, wire strippers, shrinkwrap insulation, electrical tape, masking tape to write labels with, etc.

Always label a wire before you cut it.

Never loom your harness back up UNTIL the engine has been installed and it running great. That means test it for a few days first. It's a MAJOR pain to unloom a harness that you just loomed up because you forgot to hook up a wire!

Soldering: once you have the two wires you want to solder, cut a peice of shrinkwrap insulation and slide it up the wire. Then bare the two wires. You don't need a lot, just enough so that you can twist the wires around each other. Do so. Then use an acid brush or whatever and brush some flux paste onto the bare wire. Next, have your soldering iron (hot) in one hand, and the solder in the other. Hit the wire with the iron and it will sizzle and heat it up, then touch the solder to it. The solder will melt, and then it will get sucked right into the wiring. The flux paste makes it happen, it's really cool. Let the join cool naturally. Then slide the heatshrink insulation over the bare wire, and heat it up with the handy soldering iron. It will shrink over the bare wire and protect it. You're all set!

And remember, zip ties are your BEST FRIEND! Especially when putting the harness together in preperation to dropping the engine in, use them to hold the harness together and in the right places.

That's about it. Questions? Post right here.

Written by the master: Dr Tweak

Wouldn't it be easier & cheaper to just get a new car?

Like the idea though!