The AK loom comes with a number of extras. There is a block of relays specifically for the wash/wipe functions, an inline fuse for the rad fan, connectors for the back of the dash board, and some actually very good instructions.
Installing the loom, getting it into place through the various holes and crevices, making all the connections is fairly straight forward, although it does help if you happen to be a cross between a double jointed Orangutan and a gynaecologist. And if you are you have some explaining to do.
First a bit of a disclaimer. Although what follows is from the horse's mouth, as of 21st April 2020 I have yet to connect the battery and test it. So use due diligence and take time to understand what is going on yourself. You wouldn't just blindly do what I tell you surely?
And now, as of 28th May I have connected the battery and run the engine. All electrics, instruments, lights, gauges all work fine.
The main part of the loom in the cabin has a block of fuse holders and some relays. These sit on the scuttle hoop on the passenger side. To these you need to add another relay for the fuel pump. If you get it from polevolt.co.uk you need a standard relay; Ref 202552 and a holder, ref; RBS1UKIT. These relay holders lock together to form a block that can be mounted with just a couple of screws onto the scuttle hoop. The fuse holder has mounting flanges, I used a couple of 'L' shaped brackets to mount it alongside the relays on the vertical face of the scuttle hoop. The relays thus point downwards, they are quite firmly held in place but if gravity and vibration causes them to come loose I'll create a band to hold them in place.
While on the subject, when thinking about current draw, the total length of cable has to include the return to earth, so it is actually the whole electrical path that has to be considered. Most earth returns are via the chassis rails which has such a large effective cross section that we assume the resistance to be close to zero. Or, to put another way, avoid long earth cables if possible.
The battery cable needs terminating at the starter motor with a 8mm ring terminal. The tube of the terminal can be crimped onto the cable with an expensive pair of crimpers that are man enough for the job. I used a vice. But I also cut a 6mm nut in half and placed it either side of the tube. That created four pinch points on the terminal tube which is then crushed in the vice. So the cable is crimped around the circumference instead of just on two sides. As well as this I fed some solder into the joint. My soldering iron isn't big enough to get the heat into this large terminal so I used a torch to heat the tip of the terminal, wait for the heat to transfer down and as soon as the solder flows take the heat away before the cable insulation melts.
So the engine bay leg has two red wires that connect to the live starter motor terminal with the battery cable. The loom then comes up the side of the footwell and round the back of the engine.
Secured with nylon 'P' clips against the wall of the footwell to keep it away from the headers.
Connections for the temp sender and oil pressure sensors come out of the leg at the appropriate place. The brown/white wire goes to the large metal oil pressure sensor. The leg continues round and along the left side of the engine to the alternator.
The red cable connects to the large outside terminal with a nut. There are three pins in the alternator socket. Connect a jumper cable from the large outer terminal to the pin closest to the engine. Connect the blue wire from the loom to the pin closets to the wheel arch. The middle pin is unused. To keep water out, use a Superseal type plug, known as a 'pigtail'. These are apparently not easy to locate. If you got your LS3 from Roadcraft, they will supply one. If not ask Brian nicely or search websites in the States.
It is useful if you have the GEN III chassis to use the extra chassis rails to run the loom.
I have used ties known as 'flatties'. They lay better and don't have the big square block of ordinary plastic ties, which can look a bit agricultural.
The two legs for each wheel arch are very obvious. Use Superseal connectors for the lights to make sure they are watertight. The offside leg has connections for the brake light and fluid level. The nearside leg has additional connection for the rad fan. Fit the inline fuse on the live side which I am reliably informed is the black wire from the fan. Both legs have connections for the side repeaters.
The Omex ECU is positioned on top of the passenger footwell. All ECU and loom wires congregate here in a not very social isolating way as several of them need to pass back into the cabin on the passenger side. The Omex ECU is secured with an aluminium bracket at the front to hold it in place and some industrial strength sticky back velcro to hold it down.I need to tightly group the cables which are now all in the split trunking used everywhere.
Terminals are covered with heat shrink. In some places two layers are used to give strength to the joint into the terminal. I have used self ameliorating tape on the loom joints. This is much better than ordinary insulating tape. And of course grommets in all the access holes drilled at various locations.
The rear leg runs under the drivers door, up the back of the door and through into the rear wheel arch.
Along with this is the battery cable. I created two separate holes so I can get them to pass through round grommets. In the wheel arch I have drilled through into the boot to pass the wires for the number plate light and the fuel tank sender. The rest continue on to the rear of the arch and then pass straight through into where the battery is located. As everywhere else, the cables and the battery cable are enclosed in the split plastic trunking for protection.
In the boot the the battery is fitted sideways so there is space to fit the battery isolator. Behind the isolator I have cut a 15mm square section from the floor over the rear subframe. Ground away the powder coating and fixed the battery earth terminal via the isolator switch. Later this will all be covered in.
Back to the cabin and the wiring that passes back and forth to the engine bay.
From the engine bay into the cabin we have the cables from the fuel pump, speedo sensor and reverse light switch. And we have the switched and permanent live from the ECU, the blue/yellow tacho wire and the rad fan wiring from the ECU. The ECU has it's own relay on a holder. I managed to pass this through as well so I can mount it alongside the other relays so they are all in one place.
Passing back from the cabin into the engine bay, apart from the nearside leg is the wiring for the screen wash bottle. On the drivers side the wires for the heater pass through close to the heater. These do not need a relay and I have just wired it so only the fast fan speed comes on. The heat 7 device was supplied with an inline fuse which probably ought to be fitted.
The loom instructions from AK are very good but there are some anomalies. I think this loom was designed a while back when the fuel pump in use didn't need a relay, and the fan was driven from sensors other than the ECU. So there is a bit of work to do.
The two things to worry about are the fuel relay and how we get power to the ECU. I discussed the options with Jon at AK and came up with a cunning plan. "Is it as cunning as a fox what used to be Professor of cunning at Oxford University, but has moved on and is now working for the UN at the High Commission of International Cunning Planning?" Yes, I do believe it is.
Well anyway, this is how it's done.
The ECU has two wires for live, one permanent, one switched (or ignition live). On mine they are the same colour but labelled 'ign' for the switched and 'batt' for the permanent.
On the block of relays AK have supplied two 10amp fuses for ancillary stuff like cigar lighters or eight track players. There are two spare wires from these. A red wire that is permanent live and a yellow that is switched live.
The 'batt' live from the ECU is connected to the red perm live from the fuse holder. The fuse must be changed to a 20 amp fuse.
The 'ign' live needs a lower powered connection. In the loom there is a grey wire to feed the fuel pump. We can't use it as the fuel pump has to have it's own relay so we re-provision this to be the switched live to the ECU. So connect the 'ign' from the ECU to this grey wire.
For the fuel relay, AK have a diagram for connection. Pin 30 which is the switched live needs now to be fed by the yellow wire off the spare 10 amp fuse. The other pins are as per the diagram.The recommendation is to fit a 20 amp fuse for the pump. I'm going to leave it at 10 amps as according to the data, it should never draw more than 9 amps so we'll see.
Fan relay. Previously the loom was built to connect the fan using a separate temperature sensor. With some engine arrangements that may still be required, but using an Omex ECU (and probably a Canems one as well) we need to splice into the fan relay.
The instructions for that are here.
So here we connect the brown/yellow wire from ECU to pin 85
And connect the red wire ('batt') from the ECU to pin 86.
The other two pins are left as they are.
Here the Brown wire is the perm live. It may actually be red.
The red wire is the switched live and in my case is connected to the grey wire in the loom.
The brown/yellow wire is in fact used.
And that is how it's done.
