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Disposing of the relay board:

The stock relay board tends to burn connections, lose it's waterproofing (which was never very good to start with) and generally flake out. Replacing it with some waterproof connectors and a sealed board is a good idea.

The Haynes manual shows three different diagrams for '70-71, '72, and '73. However, I didn't see much significant differences as far as this job is concerned. As far as I can tell, these should work for all D-Jet cars. I've not yet taken the time to look at an L-Jet relay board, and some of these instructions will probably not work for L-Jet.

The wire colors are main/trace. A green wire with a red tracer is green/red.

There is a main trunk of wire running through the center tunnel, through the firewall near the shifter, and up through the tin. There's an engine harness that leads to various places on the engine. There are four connectors of interest on the relay board, the 14 pin (near the firewall), the 12 pin, the 4 pin from the ECU, and the 3 pin voltage regulator (VR) connector. The connections are:

14 pin
1 yellow, main trunk, starter wire from ignition switch
2 blue, main trunk, goes to G light on combo gauge
3 gray/brown, main trunk, switched +12, attached at brake switch
4 gray/brown, below engine harness, reversing lamp
5 green/red, main trunk, oil pressure light
6 green/black, main trunk, oil temp gauge (even if not fitted, may not be on '72 -)
7 black/purple, main trunk, tach signal wire
8 black, main trunk, switched +12 from fuse 8
9 green/white, main trunk, rear blower switch
10 brown, grounding point for main power relay
11 brown/white, main trunk, "optional for sportomatic"
12 red, battery + terminal, to main power relay
13 black/red, to fuel pump (+12, switched by FP relay)
14 red, from battery +, to 25A fuse on board, FP relay and others

12 pin
1 green/red, engine harness, oil pressure switch
2 gray/brown, below engine, reversing switch
3 green/black, below engine, oil temp sender (might only be on '70-'71)
4 gray/brown, below engine, reversing switch
5 black/purple, engine harness, coil - (tach signal)
6 yellow, starter solenoid
7 black/red, coil +, ignition power
8 N/C
9 N/C
10 N/C
11 green, blower motor
12 white, Aux Air Regulator (AAR)

3 pin
red, D+ on alternator to D+ on VR
green, F on alternator to F on VR
brown, D- on alternator to D- on VR

4 pin
I switched power to ECU, pins 16 and 24 on ECU
II powered by starter wire, to pin 18 on ECU (cranking signal)
III fuel pump control (to FP relay) pin19 on ECU
IV powered by starter wire, directs power to cold start valve

Using a 6 pin connector, you can make some obvious connections for the gauge sensors:

black/purple, engine harness to black/purple, main trunk (tach)
green/red, engine harness to green/red, main trunk (oil pressure)
green/black, engine harness to green/black, main trunk (oil temp)
blue, main trunk to D+ on VR (G light)
brown/white to brown/white (sporto)

The brown/white wire is "extra", as no one really has a sporto 914, but it may come in handy someday. The wire terminates behind the combo gauge, on cars that have it at all. It may not appear on later cars.

I'd use a two pin connector for the yellow (starter) wire and the black wire (ignition switch). Direct the engine side of the yellow wire to the starter solenoid using a ring terminal. If you're doing a carb setup, that's all you need. If you're keeping D-Jet, another ring terminal with another yellow wire to a connector that splits the wire to the cold start valve and the ECU. Use a connector that will take 14g wire, and stuff two 18g wires for the valve and ECU on one side.
The engine side of the black wire should go to the new main power relay (which we'll get to).

The VR can simply be connected directly to the alternator, and you can mount this in several places. Borg-Warner makes a nice solid-state VR that will be more reliable than the mechanical Bosch units. Part number R588. Goop the spade connectors in silicone and mount it to the tin someplace.

Now, the "new" relay plate. You can use inexpensive Radio Shack supplied 30A automotive relays. Much easier to get and much cheaper than the round ones on the board now. You can get a 4 position ATO fuse block at many FLAPS, as well as online in a number of places. Mount all of these to a flat plate. I would probably want to mount it either in the rear trunk, or in a waterproof box. There are small, cheap plastic cases called Pelican Boxes sold all over the place. A box roughly 4x5x2" is adequate, and shouldn't cost more than $20. If this is strictly a no rain car, you can just mount the plate to the firewall or even the stock relay board holder.

You'll need at least one relay just to make the car work. I'll detail options later. Each relay has 4-5 terminals on it, and each are numbered: 30, 85, 86, 87, 87a (5 terminal). Ignore the 87a, we'll only use the first four. 30 is the power in, so you need to hook that up to unswitched battery power (red wires from the B+ terminal). 87 goes to whatever is being switched. 85 and 86 go to the switch that controls the relay and ground (doesn't matter which is which). We'll use 85 as the switch and 86 as ground just to keep things consistent.

Run a 14g red wire to the relay plate, and daisy chain it to all of the 30 terminals on all of the relays you intend to use. Run a 14g brown wire from some convenient ground point to all of the 86 terminals.

The first relay is the main power relay, and is there to keep the current through the expensive and hard to replace ignition switch to a mininum. The 85 terminal should connect to the black wire from the main trunk. The 87 terminal needs to go to several places, so I'd put a ring terminal on the end, and put a bolt in the baseplate that you insulate from the base plate using fiber or plastic washers. Hook the ring terminal to the base plate, and all of the "out" wires will also have ring terminal on the end. Adding new switched power wires will be easy for later modifications. Power needs to go to the + side of the coil. For D-Jet applications, you'll also need to go to pins 16 and 24 on the ECU. If you're doing aftermarket PEFI, you'll also want to run power to the injectors from here, as most PEFI ECUs ground the injectors to switch them on (D-Jet reverses this).

The second relay is the fuel pump relay. If you're doing a carb setup, skip this and just run power from the main power relay through an 8 amp fuse in the 4-position fuse block to the fuel pump. If you're running EFI, you'll need this relay, and the 85 terminal needs to go to the ECU (pin 19 on D-Jet). Run the fuse, too, between the 87 terminal and the fuel pump itself.

If you want to keep the blower motor, run another relay, with 85 hooked to the green/white wire from the main trunk. Run a 15A fuse, at least.

On connectors, crimp connectors are generally better than solder connectors. Soldered connections are brittle and tend to break up if subjected to vibration. A good weatherproof connector is the Weatherpak line, which comes in many sizes, 1, 2, 4, and 6 pin being commonly available (try www.rs-autosport.com or www.speedwaymotors.com).

I hope to provide some photos later. I invite comments and bug reports.