mpsjr

Hi folks. I started this project with my dad about 2 months ago using a wrecked '91 4Runner for parts. Since the first week of work, we've run into a pretty major problem. All of the hardware was easy enough to install, only requiring a few simple modifications. We've completed most of the work, but unfortunately, we weren't able to hook the '93 harness to the '91 tranny or computer. Also, we tried changing the harness, but the '91 harness won't hook up to the '93 engine. Both trucks had the 3.0 v6 w/ an automatic transmission, so I don't understand why we're even having this problem. I guess my question is, has anyone tried this conversion before? Does anyone know what the difference in the 2 harnesses is, and does anyone know if a '93 harness will even fix the problem? I'm pretty much screwed right now. I've been without my truck for over 2 months and I'm having serious withdrawls. A used '93 engine harness will cost me a non-refundable $125 plus shipping, and there's no way to know if it will even work. If anyone can help me, I'd really appreciate it.

Thanks.

Matt

Flamedx4

What do you need the new harness for? Was the 2wd rig working fine before? The only difference that I can think of is the wiring for the 4x4 light in the dash and the ADD front end. That you can easily just do from scratch.

mpsjr

The 2wd harness was working when we pulled it. The problem is that the plugs on the '93 harness are different for the computer and transmission that we pulled from the '91. It's kind of important to have the computer hooked up. It does, after all, control pretty much everything in your vehicle. If I use the '91 harness to make those connections, I'm not able to connect the ECM harness to the '93 engine. I have the dash from the '91, so that's no problem. Also, the front end of the '91 is now in my '93 truck. That was no problem either. Neither my dad or I know enough about electrical systems in vehicles to try and "manufacture" a harness that will connect the '93 engine to the '91 tranny and computer. That's why I would like to see what a '93 4WD harness looks like, or better yet, get one to try and see if it'll solve my problem.

Flamedx4

Sorry, was thinking 5 speed, where nothing about the trans hooks to the computer....

mpsjr

It would've certainly made things easier with a 5 speed. Unfortunately, that's not the case. Anyone else have any suggestions?

Fahrenheit 451

Getting this straight in my head...you are taking a 1993 2 wd 4Runner and making it into a 4wd by swapping parts from the wrecked 1991 right?
With a quick look at my electrical wiring diagram factory service manual for my 1993 4Runner, you will probably have to swap the 1991 combination meter into the 1993, hunt for various ADD relays and switches located in the 1991, swap the ECU from the 1991 into the 1993 and so on.
Checking at ECUDirect.com, the 1993 2wd ECU and the 1991 4wd are not interchangeable. Which just makes sense really. The 1991 shows: W/AT 4WD OE#89661-35570 which is the same in the 1993 4wd with a 3.0. So, there should be a lot of stuff that will swap from a 1991 into a 1993 as far as all the relays, but from what I can tell so far, you may be better off swapping the entire dash harness from the 1991, combination meter and relays out of the 1991 4wd into the 1993 2wd. Having the ADD front end is a lot of the hassle. Maybe it's time to do an SAS while you are at it
My son is getting ticked that I'm not paying any attention to him right now and 17mo old children can be pretty insistent. So, I can get you a pic of the wiring harness diagram for a 1993 4Runner if you would like, but not at the moment. Right now I need to go build something out of blocks and change a diaper
Ok, back again for another quick bit. Ben is down for a nap and I have a bit more time to look at the wiring diagrams. I don't think you will have to change the combination meter afterall. They only show one version. No 2wd or 4wd listed separately so that should make things a bit easier. Scanning a pic now of a wiring diagram for a 1993 4wd with automatic...waiting...going to upload it to my ftp space so you can get a general idea...more waiting...old computer and a 56k modem...this could take a while...leaving it big so it is easier to get an idea of what is going on...first shot at doing this with the printer/scanner I got for my wife....not something I use generally...getting frustrated....think I'll type a whole bunch of dots while I wait.............................................. ...........................................
Clearly, I will have to learn how to operate the scanner better, but you can start getting an idea anyway:

http://members.aol.com/mfinja/4runne...unner4wdat.jpg

I can try and scan a bunch of different pages for you or, if you can, find a FSM with the wiring diagrams. It is a definite must on a job like this.
LMK if I can help you out any.

mpsjr

I tried to reply, but as soon as I hit the post button I received a "Scheduled Maintenance" window. All that hard work, for nothing. Anyway, in short, we're gonna try to splice the 2 harnesses together so that I can make the connections to the ECU and Transmission while still using the '93 harness, since all the other necessary hookups for the various relays are already there. I've already changed out the dash, and everything else is mechanically installed (except for some of the AC components we had to pull to get to the harness). We have ShopKey on the shop PC, so we have access to all of the wiring diagrams and schematics. It's only a matter of getting everything hooked up right now. If that doesn't help, I'll get Mike over at ORS to fab a harness for a 350 conversion. That should be fun. Thanks for the advice, and if you think of anything else, be sure to drop me a line.

Thanks again.

Matt

Fahrenheit 451

Changed your mind, huh LOL! That may be the way to go. I somehow got it into my head that you had the full dash out of both trucks which would have made it easier to swap out the full harnesses. Time to start studying those diagrams for relays and odds and ends. From what little I have figured out so far, it looks like two to make sure you pull from the 1991 are the ADD control relay and the A/C cut relay (4WD A/T of 3VZ-e) and the ECU.
Ok, getting bombarded with balls and dumptrucks...gotta go.Good luck!

mpsjr

We started off by dropping the front end out of the '91, and then pulling the tranny. We knew that we needed the ECU, so that was also salvaged. The engine was already pulled and installed in a '94, and without thinking, the electrical parts that connect the harness to the engine were trashed. Our first thoughts were that the conversion would be quick and simple, and perhaps they would have been had we been using a '93 4WD as the donor. Unfortunately, that isn't the case, thus the current problem. I was in attending college for a few more months after the donor truck came into our possession (my dad owns a wrecker service as well as his mechanic shop). Without really knowing for sure what was needed to make the conversion, we pulled whatever parts we thought we needed to make it work, and then sent it off to the scrap yard.

After we dropped the front end out of my '93, it still seemed like it would be an easy install. We got the '91 front end bolted up, but noticed that the '93 didn't have any brackets to hang the differential from. After a quick call to the scrap yard, we learned that the truck was still there, and hadn't been crushed yet. Our first thoughts were that the brackets were bolted on, but we brought along a wrecker just incase we needed to haul it back to the shop, which was a good thing, considering the fact that they're welded in place. After a few minutes with a torch and a grinder, the brackets were ready to be welded up to the '93 frame.

No other mods were needed to complete the install of all the hardware, so things were going pretty smoothly. We pulled the rear cluster and checked the gearing, which was the same in both trucks, and slid it all back together. I have to say, Toyota knew what they were doing when they designed these trucks. With 160,000 miles on my truck, the rear cluster looked brand new.

Now it was just a matter of hooking up all the electrical connections. Everything was going along just fine, until he came to the ECU, and I think there were only 2 wires different, although the physical construction of the plugs weren't even close to matching up. At that time, the entire dash was pulled, to get to the harness and swap it for the '91. The only problem with that has already been stated many times in this thread, now it won't hook to the engine. Had we kept all of the engine parts, this wouldn't have been an issue, but like Murphy said, "Anything that can go wrong, will go wrong."

I did find out that my valve cover gaskets were leaking, and they have since been changed, so this project has lead to some postive things, and I have been able to learn a great deal about my truck from this experience. I got to thinking about it last night. We bought the truck for $800 from a guy that had been told he needed an engine from another mechanic. We put in a new crank and a few new bearings (about $700 parts and labor) when I got it 30,000 miles ago. It was still going strong until we started messing around with it. Not a bad deal for $1,500, right? Let's hope we get her up and running again.

Babypig

The plugs for the ditributor are different, the ECU should be the same unless your going from an auto to a standard trans. The plugs for just about everything in the engine bay are different after 92. I just put a 95 engine in my 90 and it took a little extra work to figure out what went where and with what but it isn't that bad. Oh and the belts went from a regular single to serpentine belts.

mpsjr

I don't think that should matter since we'll be using the '93 harness except for where it plugs on to the ECU and Transmission. I'll try to post a picture or two of the difference in the harnesses if I get a chance, although it might be next week at the earliest.

Babypig

That is wierd cause i plugged the 95 ECU into the harness on my 90 and it worked no problem. Don't understand why one would be different unless one of the trucks is from California. Try to get the wiring harness that came from the donor truck. Get as many parts and accesories as you can, makes it much easier in the end.

mpsjr

We still have the donor truck, and have already tried using the harness from it, but it won't work. It's a possibility that the truck was from California as the previous owner was from Mexico. It could also be a 2WD vs 4WD issue, although if it were, a '93 4WD harness should fix the problem. From Toyota, the harnesses are listed as being universal for 90-95 model 4Runners. However, I know for a fact that they are different or else I wouldn't have a problem at all. Perhaps all 2WD's are the same, as well as all 4WD's being the same in that era. I'm just not sure.

Babypig

Ahh of course, 2wd to 4wd. I do have an extra computer laying around if you want. I can make it cheap, say 60 plus shipping. It's from a 90 v6 auto 4x4. Let me know.

mpsjr

Thanks for the offer, but we've already got the computer from the '91. Now it's just a matter of hooking it up and making it work.

Thanks again!

Babypig

Ahh,

Excelent, I hope it all turns out good.