To begin with, part of the electrical system appears to be original and part was added in at a later date.
The original wiring appears to be the dashboard, fusebox and engine compartment - but keep in mind the dashboard has been relocated so the wiring was probably all redone by Carmichael. And, the truck is fitted with an alternator instead of a generator. The alternator appears to be original.
Wiring for the lights, directionals and steering column was all modified at a later date.

Also, a few extras were added - front and rear fog lights, reverse lights, a windscreen washer, a 4WD indicator light, directional indicator lights and a Series III combination switch for directions, dimmer and horns.

Problems:

Directional Switch

The Series III switch on the steering column was not in good shape mechanically. It worked for the headlights and horn, but was difficult to move for the directionals and had no way to self-cancel. And, it just did not look right in the truck.

Left rear directional light

Not working, although the bulb was good.

Front Fog Lamps

Worked intermittantly

Panel Indicator lights

Some of the lights in the silver panel were burned out and no replacement could be found.

Potential problems:

Fusebox

Just your typical Land Rover fusebox with two fuses - one being used for most everything and the other there for looks. Add to that a bunch of extra wires plugged in on the fused and unfused sides of the box. Not a good look.

Directional flasher relay

An interesting bit of Italian engineering - it had connections to two indicator lights. These did not indicate left or right - the relay design was that the indicators were energised based on load on the relay. Both indicators would flash if the directionals were used as 4-way flashers but there was no way to make them do that. Add to that the relay was made in Italy and I decided it had to go.

The battery is located under the left side rear seat in the toolbox (the left front seat of a regular 109).

Main Fuse Panel

The lower fuse on the fuseblock was not being used for anything that I could find so I replaced the whole block with a six-circuit fuse block that uses blade-type fuses. It uses a single feed circuit which is OK since the fuse block only gets power when the ignigtion switch is On and can handle six fused circuits.

Auxillary Fuse Panel

As it turned out, I needed a second fuse block for circuits that needed unswitched 12V. I mounted a second fuse block inside the cab, on the dashboard to the right of the steering column. Power is supplied from the hot terminal on the starter button through a heavy guage wire. This fuse block supplies the emergency flashers and the reverse lights - I can also use it for power for radio equipment at some point.

Directional Switch

I picked up a stock early Series IIa directional switch (the type with the wheel) that was in good shape except for the wiring. That was wired in to the remains of the Series III harness leaving a provision for the emergency flasher connections. With the relays (white box) in the directional circuit, wiring is a bit strange. The relays are controlled by the directional switch; power for the relay coils comes from the main fuse block. The directional lights are turned on by the relay contacts; power for the lights comes from the directional flasher relay - which in turn (now) draws power from the Auxillary Fuse panel. It sounds more complicated than it is, but with the relays in the circuit there was no other way to handle it. The one rear lamp that was not working was just a bad connection - suprising since the lamp assemblies are fairly new.

Directional Flasher Relay

I installed a Tridon type EL13 flasher relay. This is a heavy-duty type - the flash rate is not affected by the load. It can handle up to 10 27W lamps. Has three connections for power, load and pilot light so wiring was no problem. And it's easily replaced.

Horn

The Series III switch setup was wired to switch 12V through the horn button (on the end of the switch) to the horn relay (white box). A standard Series IIa horn push switches the ground connection. Since I wanted to use the IIa horn push, I had to rewire the horn relay. While I was at it, I replaced the single horn with dual horns (from a Morris Minor). They sound much better.

Headlight Dimmer Switch

This was fairly simple - I just installed a floor dimmer switch on the dashboard to the right of the steering column. The headlight High and Low beams are controlled via relays in the white box so the dimmer switch only has to turn on the relays. Having the relays has one side benefit - the headlight current is not being handled by the Land Rover light switch.

Emergency 4-way Flashers

Something I felt the truck needed. I installed a NOS Lucas emergency flasher switch in the silver panel to the left of the steering column, replacing one of the (no longer needed) indicator lights. The switch is wired so that it breaks the circuit for the directional switch and makes a circuit to both directional circuits. But, the directionals are relay controlled - so it only turns on the relays. Power comes from the Auxillary Fuse panel so it can be used with the ignigtion off. Power for the lights of course is done the same as with the directionals - through the flasher relay.

Front Fog Lamps

These are controlled by a relay in the white box. Power for the relay coil comes from the main fuse block, so the lights only work with the ignigtion ON. With the new main fuse panel these now have thier own fused circuit. The lamp assemblies had a lot of internal corrosion which accounted for the intermittant operation.

Rear Fog Lamps

The rear fog lamps were wired so that they would only turn on with the low beams. This was handled by the low beam relay in the white box, so the low beams and the rear fogs share the same fuse. The only change I made was to change the switch for the rear fogs and add a relay. This allows me to use the rear fog lamps as part of the emergency flasher circuit.

Reverse Lamps

The power source for the reverse lamps was from the main fuse block but I moved it to the auxillary fuse block. These lamps are manually controlled by a switch in the silver panel, so they could be easily used for work lights if need be. Future project is to move them to above the rear door.

4WD Indicator

This is the big square red indicator in the silver panel. It turns on only when the transfer case in in 4WD high. Power comes from the main fuse block and it now has it's own fused circuit.

Cold Start Circuit

Doesn't really do anything as the carburator has no connection. It now has it's own fused circuit on the main fuse block.

Indicator Lights

The non-functioning indicator lights in the silver panel were replaced with lights from a local source.

I was going to install the searchlight, blue beacon light and siren on the roof. I also had a set of two-tone air horns to install on the front crossmember by the radiator and the Winkworth bell on the front bumper.

There was also the question of a control panel. But where? The logical place to me was above the windscreen. Easy to reach from either side of the truck and out of the way.

Then, there is the question of wiring. The bell and the beacon light draw relatively low current but the other devices need a bit more power. I didn't want to use heavy switches. I decided that relays were needed.

I thought that I could install the relays in the engine compartment but I decided to install relays and a fuse panel in the original bulkhead on the right-hand side. A cable runs from the control panel to the relays. Heavy cables run to the devices from the relays. Each circuit has it's own fuse and a sixth fuse is for the control panel and relay coils.

I also installed a master switch in the silver panel to the left of the steering column to prevent accidental blowing of horns, etc.