OK. I finally got all my pictures together and edited them with some notes and arrows where appropriate. The following information explains the problem of getting the fog lights to work, and how I went about fixing it with the help of others. I won't be talking in detail about the indicator stork fitment or the relay under the bonnet, as Choady has already described the process extremely well. So, lets get straight into it...
With regards to fog lights on the 2012 GL-R triton, there are 2 problems. (I can only assume the GLX is the same)
1. The first is a missing wire from the ETACS unit (under the driver side dash) to a plug near the ECU (under the passenger side dash against the side wall). This problem is a little fiddly to fix, but it can be done relatively easily. I'll provide complete details below.
2. The second is getting the fog light indicator to display on the dash. I haven't been able to resolve this yet. What I do know is that when you turn the fog light switch on, it sends a signal to the ETACS unit, which then turns on the relay under the bonnet (assuming the missing wire is in place). It should also turn on the dash indicator, however, because the GL-R does not come with fog lights out the factory, this feature is disabled in the ETACS unit. Now apparently, its a simple matter of downloading the vehicle configuration file, changing the configuration to enable the dash indicator and writing it back to the ETACS unit. The problem here is that no one seems to know which setting needs to be changed, and the configuration file is not very descriptive. Maybe someone else has had some success in this area.
Now back to the missing wire.
The GL-R is factory fitted with fog light wiring under the bonnet. If you get under the bumper, you will find a loose plug where each fog light would normally be located. All that's missing under the bonnet is a relay, as Choady indicated at the start of this post. Also, all switches from the indicator stork to the ETACS unit are signal based, so all the necessary wiring for that is there. Once again, all you need to do, is remove the cover around the steering column, unclip the old indicator stork and clip in a GLX-R indicator stork. Now, switching on the fog light sends a signal to the ETACS unit (under the drivers side dash), which then powers a wire to the relay under the bonnet (next to the battery). Unfortunately, the wire from the ETACS unit to the relay is only half there. A segment from the ETACS unit to a plug on the passenger side, under dash side wall, is missing.
So here's a wiring diagram I managed to get hold of. It a scan of a photocopy of a printout of a print-screen, so the quality is crap, but it gives enough information to describe the issue.
I've highlighted the missing wire in red. It shows that it goes from pin 3 of plug C-33 (located near the ECU) to pin 67 of plug C-219 at the ETACS unit. The following 2 images I took from a workshop manual to identify the pins of the plugs in question.
At this point the first thing I suggest is going to the wreckers and getting some old plugs with from under the dash of various models. This image shows the sort of things I mean.
What we are interested in are the crimp terminals. These are near impossible to get hold of from Mitsubishi, so we get a number of different sizes, (and there are a few different sizes to choose from), which we will lengthen by soldering wire between the two short wires with the crimp terminals. Once you have a number of wires with crimp terminals, you can then start getting to the plugs.
The first plug I started with was C-33 which is located alongside the ECU, under the passenger side glove box, against the side wall. The following picture shows the ECU in place.
The ECU needs to be removed in order to get access to plug C-33. This is easily done by pulling down the white cam levers of the ECU loom connectors and removing the plugs. Then removed the two screws, and you can then lower the ECU out of the way. Note, that it would be helpful to remove the glove-box in order to give you enough access to the ECU, especially when replacing it, after fitting the fog light wire.
The following image shows the area of the ECU, after it has been removed.
The next image shows the plug we are interested in, C-33, after it has been disconnected from its mate.
Originally, the plug was clipped onto the wall. It is necessary to remove it from the wall to make it easier to fit the new wire.
In the next photo, you can see the existing wire from the relay under the bonnet going into the plug, but no wire in the same hole of the other half of the plug.
This photo is another view of the same plug, looking at the pins.
Finding a second hand terminal and tail (which you got from an old Mitsubishi) and which matches the terminals in the plug, fit it into the appropriate hole as show in the supplied diagrams and pictures.
In my case the crimp terminal would not clip into the plug and kept falling out, so I used some silicone to glue it into place. Do not use glue. Silicone is ideal, because it is quick drying, and the wire can still be removed in the future.
Now at this point, if you connect the C-33 plug halves together and supply 12 volt onto the tail you just added to the C-33 connector, you should see the fog lights come on, for as long as you keep the power on. This will confirm you have got the correct wire. Before doing this, use a multimeter to check that the wire under the dash goes to the relay.
Next you can solder on a longer piece of wire, about 2 metres onto the tail, and insulate the join with heat shrink and insulation tape. Then feed the wire under the dash to the passenger side, taping or cable tying the cable well out of the way.
At the drivers side, under the dash is the ETACS unit. There are a number of fuses and relay attached to the ETACS unit as shown in the following picture.
The grey plug at the top of the unit is the one we need to access. To get to it, first remove all the plugs from the fuse side of the unit and ten remove the 2 nuts (one each side) holding the ETACS unit secure.
The plugs are all different and can only go back one way. I suggest taking pictures before removing the plugs if you are unsure about how they should go back. When the nuts are removed, you can pull the unit towards the driver, and rotate it to get access to the top plugs. The gray plug should be C-219.
The next picture shows where the opposite end of the fog light wire goes.
Find a suitable terminal that matches the terminals in the plug. Before fitting it, cut the fog light wire to a suitable length, allowing enough for securing against the existing loom, then solder the tail onto the wire and insulate it with heat shrink and insulation tape. You can then fit the wire into the plug.
At this point it's not really possible to test the fog lights until all the plugs are back in place. Reassemble everything in the reverse order of disassembly. Make sure all the plugs are properly seated and clip into place. I had one plug on the ETACS unit which was not properly seated, and nothing would work. For a while, I thought I had fried the ETACS unit, and it was a little distressing to say the least. After going back over the process, I found the plug at fault and pushed it in all the way, and everything started to work as expected.
Its also worth spending the time to tape the new wire with the existing loom were possible just to keep things neat under the dash.
This whole process took me about 5 or 6 hours, and that was because I also added an illuminated custom switch for the spot lights, which I positioned in the centre console in front of the gear stick. That was a little tricky to get too.
I hope this information proves useful to you.