AE86: 4AC to 4AG (16v) Wiring Diagrams?

[yellowsnow4free]

First off, I'd like to apologize in advance if I'm posting this in the wrong section.

Secondly, I'd like to say what a great site you guys have here. Great technical info and truly inspirational build logs

So onto my question.

I've been toying with the idea of swapping a 4AG into my AE86 SR5 (USDM) eventually, but wiring has always been the turnoff for me.

I'm ok with reading diagrams and soldering, but the bottom line is people want way too much $ for their GTS harnesses.

I've read in a couple forums that people have done a 4AC to 4AG swap without donor harnesses from a GTS; does anyone have diagrams for this?

Thanks,

[parrot]

Presuming you are in the US, you are making a very big mistake if you don't obtain a USDM loom. By that I mean the complete wiring harness from the car. It is without doubt the most important part of the whole conversion. It is not easy as just fitting the engine loom and soldering a few wires.

It is not as easy as you think, and will never run as well as it should.

You would be well advised to look for a rusted out donor and transfer all the parts to your car.

[Uzelac]

Cabin loom is pretty much the same, but engine bay side is very different.

Engine loom, that one from from fuse box and all that over the engine going to ECU is totally different.

btw. I'm using AE85/4AC loom with my AE86/4AGE with VEMS. Made just few modifications wiring alternator.

[yellowsnow4free]

Thanks for the replies parrot and Uzelac!

I figured it wasn't easy, but it can't be rocket science either

The body harness is the same, with the exception of a wire for the fuel pump.

Engine harness should be different, but I've heard a harness from a FWD 4AG or an AW11 MR2 would work (some wires will have to be lengthened / shortened though).

That just leaves the dash harness (I think), and I haven't found any info on "adding" the necessary wires to the 4AC dash harness.

[parrot]

In a EUR & JDM car, the body (headlight/charge) loom is quite different, incorporating amongst other things, the all important idle up circuit. The underdash loom is also quite different. There is more to it than just the fuel pump I assure you.

You're right, it isn't rocket science, but it also isn't worth the hassle. Spend the money - you have been warned!

[yellowsnow4free]

parrot Wrote:In a EUR & JDM car, the body (headlight/charge) loom is quite different, incorporating amongst other things, the all important idle up circuit. The underdash loom is also quite different. There is more to it than just the fuel pump I assure you.

You're right, it isn't rocket science, but it also isn't worth the hassle. Spend the money - you have been warned!

Yeah, that's the conclusion I came to as well

I've come across a couple sellers who want way too much for their GTS harnesses, but if you're able to get them for a fair price it's worth it.

Ironically, since posting this I've decided to keep my 4AC Still, I was curious as to the rigor of doing the wiring yourself

Thanks!