AE92>ADM86 wiring questions

[Bray]

So on the final legs of my first ever engine conversion. Now wiring scares the absolute shit out of me because I have no understanding of it and I want to change that and understand whats going on.

The engine gone in is AE92 Smallport.

All the original 4AC loom is still in the car and engine bay.

This is the main body plug which connects to the other big plug end in the engine bay which goes off to the gearbox plugs, starter plug and i've got marked here "Temp sensor" plug.


This next photo is all the wiring that isn't connected to that main plug and goes to all the lights and heaps of other shit, AC plugs, coil plug etc.


Now i've got a complete FWD AE92 smallport loom here, what the feck has to happen, do the two looms get merged, what needs to be removed etc.

[Matt]

Being very brief you need to modify the ae92 loom to get power to what it needs for the engine to run. The first picture you posted mostly has the connections for the gauges inside the cluster and reverse lights. Those things you need to sort out are

- starter motor
- alternator
- ecu power
- injectors
- igniter
- coil
- warning gauges etc

Where you are at now is where most engine conversions fail and get abandoned because a guide on the Internet has been followed in correctly and the wiring totally messed up. If you don't spend the time learning what needs what, it is very easy to get wrong.

If you can afford to, hit someone up who has done a heap of these before to do it for you and you will be driving the car by the weekend.

The neatest way to do this conversion is to modify the ae92 loom to have the ae86 connectors on it. And to achieve the best result will take sometime.

[dogan]

The smallport loom also needs to be extended by about 50-60cm.

When I did my Smallport conversion, I pulled all the conduit off the loom and pulled out any cables that were not connected to the 2 ECU Plugs. After that I cut and soldered 50-60cm extra cable onto every wire coming off the ECU plug. Then you will need to route the loom around the engine bay to get it looking neat.
Doing this will get your ECU connected to the motor, then pretty much all you will need to do is wire up the THIRD ECU plug. Easy!

Have a read through this page and I'm sure you will have a much better understanding of what you will need to do.

[Bray]

@Matt

Yes I agree this is the part where i'm like fuck this i'm over it sell up. But since I started it I've been trying to do the whole conversion the right way the first time so it isn't a huge mess and thus far that has succeeded. I do have the opportunity to have a bloke do the whole thing for me, but it means I don't get to learn and understand what has actually happened and how it works. In no rush to get it done so if I were to attempt to wire it myself I'd map out what has to happen and take the time to do it.

@Dogan

What you've said is making sense to me for the engine loom itself. What did you do about the existing 4AC loom that is also attached to all the headlights etc and has the positive terminal on it, did you use the original Pos terminal or the Smallport one?

[Matt]

Ok cool, happy to walk you through it but for the info to be useful you will have to understand what is going on as well / learn.

Do you have the wiring diagrams yet?

[Bray]

I've got this one.

[dogan]

The loom going to the headlights Etc, just leave as is.

The cable coming off the positive terminal goes off to the alternator. The 4AGE Alternator has three pins coming off the plug at the back and that will need to be wired up too. I can't remember which pin goes where but one is for 12v Ign, one is for 12v constant which could be spliced off of the thick white cable coming from the battery +, and there will be another pin for the dash charge light which can be found on the big round firewall plug you've got a pic off.
There was a diagram I think on the page I linked to before showing which Alternator pin goes to where.
That's basically what you need to know about the positive terminal.
I used the wiring from the Smallport Alternator wiring and connected that up to the standard positive terminal.

Once you start stripping the loom neatly and carefully, you will start to see what you need to do.

[Matt]

The ecu has inputs and output pins. An input can be a sensor or straight voltage input.

The starter for instance (sta) pin on the ecu is fed voltage whilst the starter motor is cranking. The voltage input is detected by the ecu and the timing is locked to assist with easier starting.

The fp pin is an output, where the ecu will switch the pin to ground and effectively earth the fuel pump relay. Fortunately most of the wiring of inputs / outputs are contained in the loom itself and there are only a couple to worry about.

You understand how relays work yeah? Allot of the features controlled by an ecu are done so by providing and taking away the earth. Check engine light is a good example of this, the globe comes on only when there is a fault or the car isn't running.

Also if you don't own a multimeter head down and grab one as it will make your life a hell of allot easier. Get one with a buzzer when you do a continuity test as it is one you will use allot.

Wiring isn't scary if you write up a list of things to do and tackle one at a time, one of he hardest parts is routing the wires neatly which comes with experience. I'll find posts I've written for alternator and fuel pump wiring and 3rd ecu plug and link them here.

I know some things I'm writing you would already know,but I'm sure someone out there will find it useful.

[Hen may possibly be a nut]

It's really worth investing a few evenings looking at your car and learning how to read the wiring diagrams. I always find it seems impossible to understand at first, but then after a bit of looking and prodding Things start to make sense.

As an outline, leave all wiring in the car that doesn't connect to the engine. That's headlights, blinkers, horn, and all stuff like that. From memory there are only a handful of wires that connect from the car to a 4AC. Most of them are in the plug you pictured (reverse light, temp sensor for dash gauge, starter signal, etc). There's also the alternator as Dogan has mentioned (this is slightly trickier as the 4AC alt is externally regulated while the GE one has an internal reg) and a wire or two to the carb. So sorting these few wires out isn't hard.

Then there's the wires needed to run the engine. I'd recommend connecting the loom up to the engine and peeling the cover off everything. Then by looking at it with the wiring diagram you can Work out what every wire does and removed the irrelevant stuff. You can also find out what connections you need from the car (mainly +12V and earth). Then extend/trim the wires to length and make a neat loom. Then start her up and enjoy... or that's the plan.

I'm not far from Bendigo so could possibly come past some evening, but am away for the next couple of weeks. Drop me a line if you're still scratching your head at the end of August.
Hen

[Bray]

Hey guys. Had a read of all your replies this morning before work. Got home super motivated and feeling positive about the whole ordeal thanks to all your information and stripped the loom back to it's wiring, keeping a few little covers on them which shouldn't be too much of an issue.

So now I'm at the stage of figuring out what I can cut out and remove from the loom.

@Hen , that would be sweet man ! Will be happy to supply some evening beers or whatever for any sort of help !

Pics related.