Wiring and Harness question

[brandon6976]

Hey guys bit of a newbie question. I was wondering about the 2jz or 1jz (I don't think the engine is overly relavent to my question) wiring harness.

I'm not afraid of things like making mounts and that sorta stuff, however the supra is the first car that I've owned where I've thought about changing the engine. So I'm a little curious in terms of how the very basic overview of the wiring works.

I understand for example that if I get a 2jz it'll have a harness coming off the engine that I assume goes to either directly to the ECU or to a body harness that goes to the ECU. I saw http://www.norbie.net/Project2JZ/Phase8.htm which shows the mess of wires and I understand the wires would have to be traced from the original say oil pressure from the stock dash to a wire off the new harness/ecu from the 2jz.

What I'm mostly curious about is that do all the stock components such as the all the gauges on the stock dash, heat, volts, a/c switch and any other little things come to one main connector that you would/could in theory make an adapter for? Or does the stock car have several "connector blocks" where the wiring connects ?

[Junkie]

What you do,is buy the Factory service manual,and electrical supplements,for both your car and the donor.Then start matching wires.I haven't done a JZ,but I have looked through the 1 93 electrical supp. that I have,and it's not much different than wiring a 7m.That said,I didn't sit down and figure it out,just spent an hour or so going the the manual one night,I'm sure I missed something ;)

[brandon6976]

yeah i totaly get they have to be matched up.

What I don't know and more where my question is directed is more to the tune of I've heard for example if i want to change my 5m to a 7m that there is an adapter that a couple people make that'll make it so the 7M plugs into the Mark II "body" harness. So what I'm wondering is if the 7M with the adapter plugs into the Mark II body does that mean all the wires under the dash for all the in car electronics meet at one spot where it connects into an adapter ?

[Junkie]

To answer your question,are they all in one place .... Kinda.

You can either totaly hardwire,and have wire possibly running everywhere.Or,you can figure it out,and build something like this .....I believe the adapter you speak of.
http://i66.photobucket.com/albums/h242/srpmech2/87-83%20wiring/DSC01125.jpg

There are several guys here,that could possibly help,but they would also have to have the manuals.Also,to be able to build the sub-harness "adapter",it's best to have a complete donor car or at minimum a 1/2 cut/front clip so you don't have to find plugs to adapt into the car.

[brandon6976]

cool stuff. I think that answers my question. though that picture doesn't look like a complete adapter since one end is wire rather than one of those plastic adapters


I totaly get that I would have to have a donor car with the wiring harness' from both so I could make a middle/sub harness. I was more concerned with if I did that would it all be in one spot or would there but wires going all over rather than having a middle sub harness

[Junkie]

So far,nobody has a sub-harness that just "plugs" into the car.I think Jim King's may have less than that,but that's the closest I can get under the dash.Then there are 3 wires under the hood.at least for a 7m.

[Norbie]

All of the stuff you want to connect to comes off the "body" plug on the JZ ECU, and most of the stuff you want to join those wires to are in the original body plug. There's actually not much to join: water temp, tacho and check engine light are the only things going to the dash in my car (forget about oil pressure, the gauge is different), and the rest is power feeds, starter and fuel pump. In all there's probably 10 wires max you need to match up.

The mess of wires in the photo you linked to above is pretty scary looking, but almost all of that never got used - I basically chopped off the plug going to the ECU and ignored the rest.