wiring, relocating fuse boxes ect

[NIZLAH]

Hey just after a bit of help with my intentions of relocating all the engine bay fuses and relays etc.

Auto electrics is not my strong point, but I'm trying to get my head around it all.

Anyways I'm on the verge of dropping my 20v in the bay, and along with that will be a super neat loom made from scratch to be used with an adaptronic ecu. My goal is to have the minimum amount of visible wiring in the engine bay while still having everything accessible.
Basically this has more to do with the body loom, but a few things will still apply.

The battery will be behind the passenger seat also

Now my plan is to have a 8mm or so thick piece of alloy (big enough to mount everything on 300mm x 300mm or so) under the passenger side of the dash/foot well area.

I'm mostly after a list of the things I will need to gather before piecing it all together.

So far in my head I have it kind of mapped out like so....

Positive from the battery into a distribution block (fused with the main things usually connected directly to the battery) and a bypass straight to the starter motor.
This will then go to a blade fuse box for all the other smaller fused items like headlights etc...
I will mount the relays at the top of the panel (can only think of headlights and circuit open relays - what else am I missing?)
For the relays I will have some form of common earth for them to share.
The other thing I can think of that I'll need is a 12v ignition source (into a distribution block also for the various things that will require it)

Does this sound ok? what have I forgot, what else do I need to take into consideration etc..?
My apologies if it is a bit vague, Ive never done this before and its all kind of in my head how I'm going to do it so a little hard to describe.

Also to note is I will be setting up a push button start ignition with switches for the fuel pump and what note, but this will be another topic all together possible...

All help most appreciated... sorry about the long ass post..

Niz

[Golberg]

I would strongly recommend you do not attempt this.

Its one thing to relocate a fusebox, its another to basically make a collection of fuses and relay's from scratch to replace it (that's the impression I was getting from your post). Typically I'd also say that this type of OEM harness modification should be left for track only cars.

I've been requested to relocate a fusebox during a 4AGE harness job. I did it, and I will never do it again, total waste of time, just a big fuck around. You will also find that nothing works more effectively than the factory harness and fuse box arrangement.

In order to do what you are planning, you will need an advanced knowledge of exactly how everything electrical works in a sprinter.

There are also other things to consider, including the fact that it is both illegal and unsafe to have an ignition triggered fuel pump. This one thing people typically overlook.

Sorry to put a dampener on this for you, but I honestly see no good reason to do this, you're way over complicating something which need not be. And with the ever increasing number of questions on the forum which say "my 4AGE wont start" and then it being made apparent that the owner of the car has wired it themselves and typically has no real clue as to what they are doing. The majority of these questions just result in the owner concluding that they should have just taken it to an auto electrician to begin with.

The less you modify from factory in the car, the less places you can make a mistake.

I seriously encourage you to do it yourself, but not in the way you are planning. A typical harness can actually be quite easy if you have spent the hours upon hours, researching, reading & understanding what you need to know.

[NIZLAH]

Yeah I totally see where your coming from man... I appreciate your input greatly.

I was thinking of it as a way of un complicating it all (wanted to do it like so for a few reasons - like to tidy up a lot of loose ends under the dash, and make a lot of connections common/shared and to bypass the ignition barrel as it used to play up all the time when my car was running, like the engine would just switch off at random, sometimes I could flick the key and it would be good, sometimes Id have to drive for 1/2 a fucking hour while trying to hold it between Acc & start)...

also not sure if you gathered exactly what I want to do.. (not sure) but I only want to move all the stuff that you would find in the engine bay into the cabin... everything else (like the fuse panel in the drivers kick panel) can stay where its at.
I really didn't think it would be all that much and would be fairly simple-ish... if I worked backwards.. ?

As I said I will be using a new loom made from scratch for the engine.. after that I'm only really left with the headlight loom that runs under the rad support panel and a few other odd wires for the dash signals I think.

please correct me if I wrong and a little ahead of myself...

In regards to the fuel pump it wouldn't be any different from normal, instead of turning the key you would just flick a switch instead... why would this be illegal? it would still be run through a relay like factory etc.

cheers

[Golberg]

Here is a little something I noticed the other day:
*link removed*

And I was talking about just removing the engine bay wiring. There is a surprising amount which goes through the harness which loops around the radiator support from the bottom of each pillar.

It contains wires for:
Headlights
Horn
Blinkers
Parkers
Airconditioning
Automatic choke
Windscreen washer
Ignition
Batt + (to barrel & other components under the dash)
Alternator (typically runs into the main fuse box amongst other places)

Obviously you don't need a couple of things in there, but there would be a couple more things too which I haven't thought of. The thing about it though, its easy to think about each of these things individually and think about how they can be individually wired. Problems start arising with some of the ways Toyota typically wire things, and whilst you'd anticipate something to work one way often they do things in a way which doesn't seem logical (it is logical if you go through the entire loom and see how they've put it together, but this is the point I'm making you need to think about the car's wiring as a whole). I don't know if that makes much sense, but an example for you. The reverse light circuit, typically I'd think that would be a negative switch (when in reverse the wires are grounded the lights are on). But no, its not, its actually a positive wire which runs through the gearbox and to the tail lights. There are reasons why they do things like this, the majority of the time is in relation to failsafe's. Toyota go out of their way to ensure that if specific components fail, then the entire harness isn't going to melt, that only that component will need to be replaced.

I don't know if that actually made any sense, but I guess the point is that Toyota have done a lot of work to make the best working and safeguarded loom from factory. And in particular it can be quite easy to get lost in relays when you have a lot of them, and you may find that things are triggered when they really shouldn't be. And by this time, you've already bypassed the safeguards they've put in by removing the original wiring.

So typically if it were me, when wiring a 4AGE I break the system down into 3 sections:
Alternator/Power Source
Engine Harness
ECU power/fuel pumps (typically 3rd plug when using a factory ECU).

If you approach it that way its pretty easy to make a very clean setup.
This is approach suits the original layout of the car's wiring. This is because you can typically run solely the Alternator/Power Source harness straight off the original engine bay fuse box and run it neatly out of the way along the radiator support and over to the alternator. The engine harness will then only run to the hole in the wirewall over on the passenger side, and also to the plug which sits in the middle of the firewall (big one) and nowhere else in the bay apart from things actually on the engine. And the ECU power/fuel pumps related wiring is then directly grafted onto the dash harness.

Setting things up this way also allows the system to be easily be put together with plugs, and so in the event of having to remove the wiring its very easy.

Its kinda hard to explain without photo's sorry. But if you keep an eye on pen15's rides thread he should put photos up of the job I just did on his KE70 (basically the same layout as what I'd on an AE86) very soon.

In relation to the pump thing, its got to go with being a crash. Say you roll the car, engine will probably have stopped, but if you rupture a fuel line, your pump will just keep pumping out fuel everywhere. Which of course is a massive fire hazard. A typical Toyota circuit opening relay solves this, as the ECU only triggers the fuel pump/s when it detects that the engine is running. Circuit opening relay also turns the pump/s on when you're cranking because the computer may not detect it as running yet. It is however possible to have a momentary override switch (as I did in pen15's car) which allows you to trigger the pumps when ever you're holding down a button. That in particular is useful for diagnostics if there are issues and also to prime the fuel system (although typically there is no need).

Hopefully that clears things up a little more for you, and please excuse my earlier aggressive tone. Typically I don't even answer auto elec questions because they tend to frustrate me, especially when they say "help, my engine wont run". But you seem to be more interested in actually working this stuff out before you run into problems, which is certainly a good thing.

[NIZLAH]

Another great answer, thanks man, your starting to convince me lol....

I guess it comes from my lack of knowledge on the subject, but I didn't realise/consider that a lot of the circuits are combined with other things, so they can not be routed individually like you state (without difficulty anyway)

I guess then, the only thing I would like to do is move the fuse box that sits on the passenger side in the bay to in the car..... correct me if I'm wrong again.. but would it be as simple as extending the wires that connect to it and running them under the guard and then into the cabin out of site to where it would be mounted?
And again the same with the 2-3 relays that usually sit on the strut tower..

Fuel pump - yeah ok that makes perfect sense... I should have realised that...

I'm sure there was more I was going to say/ask but its slipped my mind at the moment.

Your help is appreciated...

Niz

[FAST EDDIE]

i relocated the stock relay and fuse box in my 86 street car under the dash i just chopped and joined the wires, works as effectively as if it were under the bonnet but as stated up further if something goes wrong how fast can u kill the power!!!