AE92>ADM86 wiring questions

[Hen may possibly be a nut]

Looks good. I'd recommend plugging plugs where they belong on the motor, so you can see where plugs should go and which wires go where.

A bit of time with the wiring diagram (using the colours shown on that helps alot to identify things, though sometimes they don't match 100%) and a bit of common sense (like the things connected to the battery clamp get +12V) and it should become less mysterious.

Hen

[Bray]

Running it around the engine trying to work out what's what. Injectors, map sensor and TB shit is all sweet.
Rest gonna take some research. What can I 100% cut out, eg. Powersteering/aircon related plugs

[Matt]

I use these to de-pin the wiring looms once you lift the white clip on the plugs to unlock them.

I start by separating the starter wiring and keep that in tact as is.

I then also separate the alternator loom wiring as in the JDM ae86 looms it is ran stand alone as such and routes in front of the radiator. You should find you can pretty much remove the alternator wiring along with the thermo fan wiring without cutting anything. When looking at what connects into the ae92 fusebox, it is pretty much only the alternator charge wires, high amperage input to the open circuit relay and power feeds from the battery for other relays.

Whilst this is a shitty pic, it outlines what is what in the plug that goes into center of the cabin.



I recommend removing the wires for the oil pressure, temp gauge and reverse switch from the loom and adding them back in at the end when you are making things neat.

The ignition wires that need power also go into the centre of the cabin on the ae92 which are outlined in this shitty pic plug too



Then what is left is the Fuel Pump Wiring . is a guide i wrote ages ago on the fuel pump wiring.

And finally the 3rd ECU plug, which is quite straight forward.

That should be a heap to get you going, just remember 1 task at a time and once you complete it move on to the next. Double check if you are unsure of what you are joining something into, because once you let the magic smoke out of the ecu it won't come back.

[Bray]

Okay. So spent a bit of time reading over this a few times to help it make sense then went about sorting through the loom before I remove anything.
Thus far the plugs i've got sorted are;
1. Injector plugs
2. MAP sensor
3. The water sensors at back of the head

This is where it started to get tricky, the alt wiring runs between one of the ECU plugs and another plug which i'm guessing is the AE92 Body loom joining point? Pics related.


@Matt
When you say to de-pin the wires, do you mean from this ^ plug so the alt wiring is only attached to one of the ECU plugs. OR would it be better to cut the 4AC ALT plug off and rewire the 4AGE one on to the original 4AC loom in bay.

More: The O2 sensor I have is completely different from the one on my extractors, this is pretty much an easy fix but may be easier to just remove it completely and worry about it later.

There is so many random plugs on this loom its ridiculous, eg. The AE92 fuse box plugs.
My loom didn't come with a 92 fuse box, am I supposed to have one to replace the 4AC one?

[Matt]

You modify the loom to mate into the ae86 fuse box where possible. Most people add in an external relay to make the task easier and avoid the integration into the fuse box.

Another thing to note is, it doesn't matter what order you connect the injector plugs in as they are batch fired.

Alternator Wiring

The last post you made is 100% the body plug, the alternator wire in there is for ignition power. The yellow wire is for the charge light and the small white is the voltage sense. The thicker white wires are the ones which actually deliver the charge current to the battery.

For an alternator to charge, it needs ignition power. The regulator detects the amount of charge being outputted via the sense wire and ensures the voltage going to the battery is ~14 volts. If you don't have the sense wire connected the alternator can charge at 20+ volts and cause your battery acid to boil and cause the battery to swell.

The charge wire is an earth connection whilst the alternator is not charging. The second an alternator starts to charge the battery, the earth is removed and the light goes out on the dash. As the globe has ignition power, this is how you get the warning light that an alternator is failing when driving.

All of the cars i've wired, I grab the smaller sense wire and solder it onto the thicker charge wires. Whilst this is technically not correct, it hasn't caused a problem in the conversions i've done. Theoretically if you have a break in the thick charge cables to the battery than the alternator will think it is charging when it isn't.

In the ae86 the voltage regulator is external and is the box near the battery, where as in the ae92 it is built into the alternator. So the wiring won't match 100% between the 2 and needs modifying.

Hope this helps explain the the alternator wiring, it is really simple but allot of people fail to understand that the charge wire is an earth connection. Once you separate the alternator wiring and route it along the bottom of the radiator and connect it up to the original ae86 wires, you will find the wiring allot neater.

[Bray]

Good explanation on the all wiring. I understand that completely now so that should be sweet.
i want to eliminate some of these plugs cause surely I don't need half of them.
Can I delete the diag port including all the wires that come off it, anything heating/cooling related.

Also what's the trick to removing that white clip out of body loom plug, doesn't want to come out.

[Matt]

I wouldn't delete the diag port as it lets you check codes from the ecu if u need to troubleshoot. Delete the air con though.

as for the white clip you just raise it up and it releases it but it stays on the plug as such

[Matt]

Concentrate on the wire routing now, put the coil just behind the battery and extend the wires to reach. Diag plug can sit on the firewall in front of the passenger seat. The rest is pretty much fixed position.

[Bray]

Starting to get it routed now. Few questions

1. ECU has the 26&16 pin plugs but no 12pin plug, what does 12pin plug do
2. COR plug doesn't seem to be there but may have wire tunnel vision and can't see it
3. All the wiring attached to the AE92 body plug, does it all end up attaching to AE86 body plug
4. Have a plug here that has a funny looking plastic black wizards hat on it.

[Matt]

The 12 pin plug is the plug required to get power to the ecu. It requires constant power to retain the memory of the ecu and ignition power.

It also provides the earth for the fuel pump relay for when the engine is running as well as the earth for the check engine light.

You will find the circuit open relay in close proximity to the 12 pin plug. Allot of the time people don't sell engines with the 12p plug as it involves cutting it off the body loom