travisamorgan

I have been reading and reading for about 4 months now on this swap. I finally got the money to buy a 3.4. I am picking up a 3.4 from a 99 4runner automatic. I plan to swap it into a 94 3.0 pickup 5 speed. I will have the auto ecu and auto wire harness and all the sensors needed from the same 4runner.


my questions are towards the wiring.


1. I have read multiple times that the plugs and pin locations in the harness are the same for manual vs automatic 4runners after 98? am I right? if that's true I should be able to just plug in the engine harness and just possibly re-pin the body harness inside the cab.


2. The ecu will run the engine with the stock unchanged engine harness but just throw codes for the transmission stuff (the speed signals and such) right? The only other problem would be the neutral safety switch that would prevent it from starting but it should just need a ground to bypass it right? I don't have emissions to worry about.


3. If I need the manual ecu and engine harness, do I have to find one from a 99 manual 4runner or would one from a 99 Tacoma manual work? (I read something about the tacomas having egr and the 4runner not?)


Thanks Travis

JasonYota

iTrader: (1)

Yes you will have to repin your dash harness, the auto and manual plugs are the same for that year and up.
I ran an auto ECU a few days, engine codes were thrown for the trans.
I went ahead and bought a manual 4runner ECU, tacoma's were cheaper though, might throw codes for the egr I'm not sure. Mine started out as an 2000 automatic 4runner 3.4

SacRunner

Look at the following screen-grab of a 97 4Runner 5VZ ECU EWD:


You'll notice that there are two circles with letters in them on each of the wires leading into the ECM, the top one is for M/T ECUs and the lower one is for A/T ECUs. Look at the EWD for your 99, if there are 2 sets of connectors for each connector (as shown above) there are different pin outs for M/T vs A/T, if there is only one, there's a good chance that the pin outs are the same for M/T vs A/T (I only phrase it like that since I have never actually seen an EWD newer than the 97 I have).

I would suggest creating a "conversion harness" that plugs into the 3.4 engine harness (leaving all the pin outs the same, so they still match the EWDs) and connects to your truck's body/dash harness (again, leaving all the pins the same). Doing this allows you to restrict the wiring changes to just the conversion harness, and its a lot easier to work on it at a bench or table, rather than in the kick panel. Of course you'll need the connectors off your 3.0 that connected to the dash harness, and the dash side connectors from the donor that connected to the 3.4 engine harness.

I can't really help you here, but I would be cautious with a set up that always has the CEL on as it could hide an actual code, unless you were to get into the habit of checking for codes on a regular basis.

travisamorgan

I got the wiring diagrams from the TIS website. It doesn't show different pinouts like the pic above so I assume they are the same.


I will only have the ecu in for awhile til I can save up the money for the ecu. I have had a check engine light on for my second o2 sensor on my other vehicle (a cut wire somewhere between my o2 connector and my ecu) for a long time and just checked the codes every month when I get a chance to stop at advance. or


I have a new question does anyone know what the connectors are called behind the glovebox on my truck are called for the body harness? The white and grey ones? I think its c1 and c2? And which connector on my 99 4runner harness do I need to repin or build a conversion harness from to connect to the dash harness? Is it II1 and II2?



I have the entire 99 4runner dash harness just no idea what the connectors are called the I need to connect to each other. I got all the wires I need traced I think from the starter, tach reference, speedo, water temp, etc.

JasonYota

iTrader: (1)

You don't need the dash harness from the 3.4, just the few plugs that go into the ECU and several inches of wire to work with.

travisamorgan

Ok but which connectors for my dash harness if anyone knows? What are they called?

JasonYota

iTrader: (1)

I only needed two dash plugs from the 3.4 which ones you need will depend what your donor engine came from and the ECU

travisamorgan

I understand that. I was hoping someone could tell me what they used to see if mine was right or give me ideas on what to look for.

Did toyota use the same style plug for every vehicle for the dash harness or does it change along with the name and pinout also. Like does my 94 pickup have the same plug as the 99 4runner?

JasonYota

iTrader: (1)

The pin outs could change year to year also from the model the donor came from. If the plugs were all the same that would be too easy lol

travisamorgan

But are the plug shapes the same? Or did they change those too?

JasonYota

iTrader: (1)

The plugs changed also

travisamorgan

Ok so I got started with the wiring. I got all the ewds for both vehicles and now I got the engine cranking but have no spark or fuel. We took a spark plug out and grounded it to the negative battery terminal and no spark across the good plug. We also hooked up a timing light we had and looked for the light while cranking and nothing either. We took the fuel line loose and no fuel coming out. (We had it in a bucket so we could catch it.)

As of now we have the +B wire to ignition on. Batt wire wired to a constant on. Igsw wire wired to ignition on source. Fc wire wired to the green yellow stripe on the 3.0 circuit opening relay. (Thats what the 3.4 swap 101 sticky said.).

What does the mrel wire go to? The ewds fpr the 3.4 show it is the power side of the efi relay control coil. The ewds for the 3.0 has the efi relay control coil getting power from the ignition fuse. Do I do anything with it?

Does the ecm need any ground wires going to it?

We havent done any diagnosing but want to make sure all the wires we have to have wired in are so it will start. I do still need to do wiribg for the dash such as the volt gauge and the oil pressure and coolant temp. Id just like to get it running. Its been 2 months since my trucks started.

Thank travis. Any help is appreciated.

JasonYota

iTrader: (1)

For the fuel pump. Did you wire the COR like in the 3.4 swap 101 sticky? Also did you wire your MAF and igniter? There has to be 12 volts to the MAF to sense air or it will not spark.

travisamorgan

Doesn't the maf sensor get 12v from the ecu? Or do I actually have to wire the 12v directly to the maf and igniter?

Yeah I wired the fc wire on the ecm to the green with yellow stripe wire at the c2 or c1 connector instead of directly at the cor just like the 3.4 swp 101 sticky said.

JasonYota

iTrader: (1)

Find your MAF in your diagrams and trace the wires back to the battery. The positive should go through one of your connectors. That's where you wire it.

travisamorgan

the batt terminal on the ecm gets constant battery right? and the +B and igsw gets 12v when ignition is "on" right?


does the maf and igniter get power from ignition switch on? ignition switch "on" is IG2?


do I need the mrel wire?

JasonYota

iTrader: (1)

In not looking at my notes at the moment. There are several wires that are wired for constant power and several for switched power.
What does the mrel wire to go? I remember those letters from my swap.

travisamorgan

Ok mrel goes to the power side of the control coil of the efi main relay. On my truck ewds it shows that it comes from the ignition fuse.

I was just checking which wires should be powered when. Batt terminal goes to battery power constant on from what I can tell and +B Terminal and igsw go to ignition switch IG2. The maf and igniter power wires are called +B so id assume they get power from the same source as the +B terminal of the ecm which should be ignition switch. I wouldnt think they are always powered.

JasonYota

iTrader: (1)

Ok here is what I done. I made an adapter harness. Figure out what connectors are used on the 3.4 body harness. Count the number of slots and wires to each plug. Find every pin out in your diagrams. Write them down. Do the same with the 3.0 then match them up. A few are different but most are marked the same.
Are your wiring diagrams on a PDF?

travisamorgan

I have all the ewds saved as pdfs. I was gonna make a conversion harness but when I was explaining to my helper since im kinda colorblind I needed to connect the wires he cut the body harness before I could tell him I wanted to do a conversion harness. I am just soldering wires for now. Eventually I might buy new pins or like weatherpack connectors and make a conversion harness with connectors once i get some extra cash. Im not working with that friend anymore for a while haha. Oh well.

I already went and made an excel spreadsheet of what the wire does and what wire from the 3.4 connects to which wire on the body harness.

I already got all the gauge stuff figured out I think and my speedometer connections figured out.

I remember seeing a thread explaining what pins get what voltage and when and I havent found it since. Ill try to find yhe diagram of the ecm terminal info I downloaded from yhe tis website. I remembered just now that I had it saved. It should tell me I hope.