joining all GND, +IGN etc at the loom

[randomskate]

Car - adm ae86

motor - smallport 4age

use - engine swap

problem - I am converting this from 4ac to 4age and extending the wiring loom by 80cm. I was wondering if i could solder all 5 grounds together from the ecu and running another thicker wire to the engine block instead of running one wire for each? can i also do this for the two on ignition power feeds too? and can i connect the neutral start switch to +ign too or do i just not connect it to anything at all?

occurs/started when - i ran out of wire

personal situation (if applicable)- ??

Thanks in advance

[Hen may possibly be a nut]

Essentially yes, you can connect all grounds and IG+ into bunches and things will work, though it's not the best way to do things.

There are two types of ground, power ground (as in ground wires where a reasonable current flows, for example the injector wires get pulled to ground to fire them and they require a bit of juice) and signal ground (very little current flows and is just used as a reference when finding a sensor resistance, like temp sensor ground and MAP sensor ground). It's best to keep these two types of ground seperate. So assuming you're using a JDM AE86 ECU E01 and E02 are power grounds (as far as I can see) while E21 and E2 are signal grounds. In any case I'd run at least two seperate wires (one for each type of ground) back to the earthing point on the chassis where the battery negative connects. Yes, running it to the block will work, but this also relies on good earthing from the block etc...

Running a single, large enough feed for both IG+ feeds will be fine.

By the looks of the wirirng diagrams on club4ag, NSW should be connected to IG+ to make it look like you're in neutral.

I'd also recommend doing it properly, don't take shortcuts just because you ran out of wire. I've seen and heard of so many projects that have been annoying due to dodgy and unreliable wiring. Do it properly (or at least reasonably) first time round and things will be much better.

Good luck
Hen

[blair]

+1 to the above comment.

My alternator wiring (until i got to it) consited of about 9 sections of wire, twisted together (NOT soldered) then taped once.

It's not fun when shit just stops purely from someone being lazy

[randomskate]

thanks alot for the advice guys. sure, nah ive twisted then soldered then heatshrinked all joints so far, then i was gonna use some electrical tape all the way down the loom and then cover that with cloth tape or maybe some sort of heat tape... was just curious to know why there are so many ground pins on the ecu if some of them end up connecting to the same place.. also there is two ignition pins right next to each other on the 12 pin plug (black/red).. why would they run two when there both positive ignition feeds instead of just running one slightly thicker wire instead? the last thing i want to do is take shortcuts or do a bad job.. i'm not goin to run the a/c wire simply because i'm not going to have a/c on the car. and just noticed NSW seems to already have no wire coming out of it... i suppose i don't need to run this to the ign anyway as it came from a manual car.. so this ecu is for manual cars only.. am i right to say this? and yeah my problem had nothing to do with me running out of wire haha, i just didn't know what to write in this trippy template. just went out and bought some more wire too i only originally accounted for the 26 pin plug alone (doh).. the wire i am using is thicker than the stock ecu wiring so this job will be overkill, not dodgy lol i'd hate to do a bad job only to take apart the loom and do it again

[Hen may possibly be a nut]

Now that I'm on a roll about wiring and how it should be done (well... according to me at least) I'd say don't use electrical tape on your loom at all. It gets old and hard and leaves sticky gunk everywhere.

Instead use split loom and zip ties (bread bag twist ties work as temporary zipties while you're running wires to work out correct length) or plastic loom tubing (the entire circle stuff that you have to thread the wires through), or spiral loom or something similar.

As for why Mr. Toyota ran multiple pins, it may be that max current would be too much for a single pin, or possibly he was just being very conservative.

Also could you please use some more punctuation and break things into paragraphs. It makes things MUCH easier to read.

[randomskate]

Ahh ok yeah I've seen the spiral loom stuff your talking about before.

You have a good point about the gunk stuff from the tape too. Should I be worried about heat? That was my main concern. I suppose the spiral loom would be the least effective against heat out of your suggestions (as it has gaps through it.)

I think I've decided I will run all wires as they would be stock, ie run both those ign wires, earth etc... would be easier I think as the loom I have is just chopped at the firewall by the wreckers from when they took the motor out of the ae92. I have a feeling that this would be the best way.

The whole point of this is to just extend the loom by 80 cm, i have both ends of it already and one side is still left attached to the motor. I was going to just leave it attached and just solder the rest of the loom to it then feed it through the firewall when i change the engine this weekend. Do you think this is a good idea?

Thanks again for the help mate, I really appreciate it.. and sorry about the paragraphs haha, hope this one is easier to read

[randomskate]

finished soldering one side of the loom just then. Wires turned out to pretty even length-wise overall varying by ~3cm but most by 1cm. Still have 3 really thick wires to do, but i need to get thicker wire for that





I didn't end up linking the ground wires etc. have a feeling something might go wrong if i do so... just need to solder the other side to the engine now!

Fun!