Wiring from scratch, not so simple! Help!

stevieturbo · Post by **stevieturbo** » Tue Dec 22, 2015 2:29 pm

chodjinn wrote:Interesting Stevie, from what I have read the dual fuel pump relays is to ensure that both pumps get a decent amp feed. But then again you have direct experience! And I wouldn't be running anywhere near the power you are. Pumps are a basic HP electric lift pump and a Sytec HP pump. I may change it to one relay then.

The FIA kill switch comes with the relay attached, you have to use them for racing to ensure total kill of engine.

I've already got the FIA kill switch, push button start/relay and a bunch of other stuff left over from my MGB project so will be using those (all new).

And you're right, the alternator is a 3/4 wire. Will have a rethink.

I'm pretty happy on the individual circuits for the moment, it's getting the ignition/battery/alternator all wired up I'm still not sure on

The number of fuses or relays dont determine whether wiring to any loads are good....wiring determines that ! lol.

You could just as easily wire it crap with multiple fuses and relays as you could with 1 and visa versa.

If it's good it's good, if it's bad it's bad.

And although there are multiple wires on the alternator plug, it may only be a single wire you need to "excite" it, just make sure you look into it and get it right.
Some modern stuff are electronically controlled, often by the engine ecu. Not 100% sore on the strategies they use whether they do actually regulate voltage or whether it's a simple trigger from the ecu

But I did manage to blow one up on a friends Subaru a few years ago by mucking about lol

chodjinn · Post by **chodjinn** » Tue Dec 22, 2015 2:58 pm

I meant that with a dual relay setup, both pumps get a straight 30a feed, rather than being split from a single relay.

According to the 1UZ wiring diagrams I have found, there are 4 wires on the alternator. There's a voltage regulator already built into it.

From what I remember in my setup, there is the main battery connection, a small fused wire (must be for dash charge light) and another connector with two wires on. Will have to trace them back through loom.

I'm going to have to spend a lot of time tracing wires and writing it all down, I can see this taking some time! But if I can do it, it would be great. Only got time to burn at the moment over xmas before I can finish painting the shell when it gets a bit warmer, so may as well crack on with this eh!

stevieturbo · Post by **stevieturbo** » Tue Dec 22, 2015 3:10 pm

chodjinn wrote:I meant that with a dual relay setup, both pumps get a straight 30a feed, rather than being split from a single relay.

A 30A feed is only a 30A feed if all wiring and connectors used are capable of coping with 30A....and then the load is pulling 30A.

You could wire a fuel pump in 35mm^2 several hundred amps capable cable...but it will still only draw the same current as say 1.5mm^2 cable.

Giving wiring names like 30A doesnt really mean a lot.

I just say the wiring/fuses needs to be appropriate for the loads that are attached to it.

As said it's either right or wrong and it's easy to do both.

But as with any electrical load, you need to factor in extra capacity for loads that will run for long durations more so than those for short duration.

My pump wiring is substantial, I use a single 70A relay and a 40A fusible link. It's overkill, but I know I can add a 3rd pump safely if need be.

And again if the relay fails, if the fuse blows, if any part of the wiring fails the engine should stop although it never has in over 10 years like that.

IMO I just dont like multiple relays or fuses for the main fuel system although I can see why some might prefer it or think it should be that way.

Also dont get confused in thinking the fuse is to protect the load. In almost every case it isnt, the fuse is usually to protect the wiring and against fire hazard but obviously fuse size is then determined by whatever load is attached to it so it can still operate without blowing.

chodjinn · Post by **chodjinn** » Tue Dec 22, 2015 3:54 pm

Yeah fair enough with respect to the wiring, I wasn't being specific enough. You got any wiring diagrams of your setup? I've already learnt more in the last day or so than in the lasts week by just looking at individual circuits rather than whole looms/diagrams!

DaveEFI · Post by **DaveEFI** » Tue Dec 22, 2015 4:17 pm

Yes - much easier to follow an individual circuit rather than trying to pick it out from a master one.

I use a CAD prog for drawing such things. DraftSight is a similar free one for a PC. They allow drawings to be in layers, so you can have an individual circuit as part of a master. You could have say the lighting on one layer and display that only - or the whole thing.

They also allow you to use either a library of existing symbols and or add to it with your own.

stevieturbo · Post by **stevieturbo** » Tue Dec 22, 2015 4:24 pm

Never did any diagrams, never really needed to. I kept things simple and retained OEM wiring for the car ! lol

When I re-did the engine power loom a few years ago I used this

http://www.painlessperformance.com/webcat/50001

But as said, I did need to modify quite a bit. That does only cover aspects relating to the engine though. ie fans, pumps, ignition, and various other items.

Fuel pumps I had to wire independently which made sense anyway as they are out back, so the relay etc for that is out back too.

Actual engine loom itself, ecu are all separate again, but this loom does receive power from the Painless relay/fuse block and loom.
Obviously the actual engine/ecu loom was made from scratch

Really for the bulk of your chassis wiring, something like this would cover a lot

http://www.painlessperformance.com/webcat/50003

There would also be a lot of wire left over which is handy for other things, but yes you'd need to spend more on top of that

Whilst this is intended for a different ecu, it's still generic and they can offer it for more injectors. Really it doesnt look like a bad price even if you did need to make some changes afterwards.

https://shop.vems.hu/catalog/v3harness- ... 8001d8fd09

Or you can do down the road of buying all the wiring parts and doing it all from scratch. It's a slow, tedious and expensive task. Especially if you want to try and keep a sensible colour scheme for the wires.

You can also find cheap relay boards on egay, which may or may not be handy. Just make sure their switching is suitable for what you need.

Some will be arduino controlled, some 12v to trigger, some 0v to trigger. Still nicely packaged though and very cheap

http://www.ebay.co.uk/itm/DC-12V-8-way- ... SwDN1UQdgB

Darkspeed · Post by **Darkspeed** » Tue Dec 22, 2015 6:04 pm

Could start with one of these to get you going in the right direction.

http://www.rapidfitlooms.co.uk/standard ... ngloom.htm

chodjinn · Post by **chodjinn** » Wed Dec 23, 2015 7:14 am

Many thanks for all the replies and links, definitely a lot to think about over xmas. I'm going to try and make what I have work, now I have stopped panicking!

I finished stripping the engine loom last night, what a task! I basically removed all the plugs that were not being used, including all the automatic trans connectors (4 of them!), EGR wiring, AFM and traction control connectors etc, tracing them back to the bulkhead connector where the Link G4 connector and original Lexus 3 ECU connectors are. I also removed the entire diagnostics connector which had 16 wirings I think (half were already cut, the rest went to the old ecu connectors).

It all went pretty well and the loom is now half the size it was, only thing I wasn't sure on was the O2 connector which had two small wires (connected to the Link) and a big wire that went to another unused connector.

The only wires I was left with to connect was the main power wire (for starter and all injectors etc), a fused wire for the alternator, one for the oil temp sensor and a big grey plug that goes to one of the fuse boxes. I went very slowly and methodical and think it is ok haha. The ignitor loom is also separate so can mount that somewhere out of the way

Last week I did the same with the car loom, I just need to go through it again and then I can start tidying it up. Then I can figure out what needs sorting out.

Darkspeed · Post by **Darkspeed** » Wed Dec 23, 2015 12:07 pm

Just take lots of notes - use lots of masking tape with identification notes - Keep a separate cheap wiring note book - stick a label on the wire/plug/socket and reference that wire/plug/socket in the book.
Take lots of photo's. It is quite cathartic when you get into it.

chodjinn · Post by **chodjinn** » Wed Dec 23, 2015 12:29 pm

Darkspeed wrote:Just take lots of notes - use lots of masking tape with identification notes - Keep a separate cheap wiring note book - stick a label on the wire/plug/socket and reference that wire/plug/socket in the book.
Take lots of photo's. It is quite cathartic when you get into it.

That's what I did when I removed the loom in one from the original car. now I've binned all the bits labeled 'not used' I'm going to re-label to help me sort it out / neaten it up. It is actually quite therapeutic ...!

stevieturbo · Post by **stevieturbo** » Wed Dec 23, 2015 5:43 pm

As above, label the f**k out of it !!!

Every single wire if you need to at various access points.

It may seem overkill, but months or years down the line you will be glad you done it ( or even days lol )

unstable load · Post by **unstable load** » Thu Dec 24, 2015 7:56 am

I have helped wire up a helicopter, and what we did was have a "loom board" made up, which is essentially a few sheets of ply wood big enough to mount the loom on. The length of the harness is run through a series of P-clips to hold it all in place and each connector is fixed to the board. Any branch-offs are a fixed point and individual runs are ID'd by system/destination(oil pressure/engine bulkhead etc).

Then, each wire is disconnected from the connector and replaced individually.
Wires in aviation are identified with numbers and are mostly all white, so it gets very out of shape very quickly if you lose your position in the process.

That's what I would do if it was my car, and that way, I could eliminate the unwanted wires and at the same time, tidy it all up nicely.
Remember, wiring diagrams are ESSENTIAL for reference.

chodjinn · Post by **chodjinn** » Tue Dec 29, 2015 10:08 pm

I've done with the loom for the moment now. I separated out the fuel pump and rear light looms. Also took out the wiper loom completely.

All that seems to be left is the main ignition/starter/fan and relay/fuse box. There is one part of the dash loom left I think is linked to the fuel pump so will be leaving that. I removed all the unused fuses and relays and was left with the ignition, fuel, main and fan relays only (and one labelled "eccs" in felt tip ....).

There is a 12v battery power feed left spare which I can connect to the new fuse/relay board I will need for the two fuel pumps, small interior fan and anything else I may need.

Anyway, labelled it all up and now boxed up for later work. Going to get on with more mechanical stuff tomorrow!

Many thanks for the tips/help so far, will be back no doubt shortly for more advice!

volospian · Post by **volospian** » Wed Dec 30, 2015 10:13 am

It sounds like I may be too late to say this, but I'd suggest you don't physically remove any wiring/connector from the existing loom until you are totally sure you won't need it (I dunno, maybe the ecu requires a specific input (say vss) but you think "Oh, I don't need tc on this", so you strip the wires and then wonder why the ecu isn't working. .. crap example, but you know what I mean:)).

As the car is track only you probably don't need a lot of the original wiring, but it's always worth triple checking every need and being totally sure before you commit to actually removing something

Also, I'd suggest you trial fit the loom before you spend time wrapping it all in tape, etc. . You don't want to fit your lovely clean taped and nicely sealed loom and find that because you changed this manifold or that gauge position the original connector no longer reaches

chodjinn · Post by **chodjinn** » Thu Dec 31, 2015 11:27 am

Hah yeah it is too late mate! I've probably spent 20hrs going over the loom. I start with the connectors that were not used in the original car I took it from - there were a lot. The lighting loom was pretty easy to remove, and there were also a lot of cut wires already. The loom is about 1/3 the size it was. I've not taped anything up yet as I will be going over it again when I get round to test fitting it to the shell.

The ecu/engine/starter loom is separate to the car loom already. It basically only has one larger connector for the battery live (main feed to starter), a fused wire from the alternator, and three connectors (fan loom, and two for the relay/fuse box).

I've save a whole box load of wiring and bits for future use ... guess I will have to see how it goes in the new year! Worse case I just start over from scratch! All a learning process I guess