Rewiring

A number of wires on my '71 were burnt near the fusebox, and the harness in the front trunk had been hacked up extensively. 35 year old wiring insulation is often brittle, the colors fade (so it's impossible to tell a black wire from a black/purple wire, for example), and connectors corrode. The fusebox had a broken "foot" that held it to the fuse panel.

There are also many things about most OEM harnesses that annoy me, most usually because they seem needlessly complex. I also had ditched several things I no longer needed, like blower motors and parking lights.

So, I'm undergoing a total rewire, which is a pretty big job. It's not something I'd recommend most people do. A used harness is obtainable, and can generally be cleaned up to work. I'm not going to do that, however, as I'm stupid. If you're repairing a car that's had the harness substantially damaged by fire, this may be helpful.

To keep it managable, I'm doing this in stages. I just installed a new engine and new brakes, and I'd really like to drive the car some before gutting all of the wiring, so the first stage will be a partial rewire, hooking up only the minimum. I'll then remove all of the wiring and replace it over the winter months.

The minimum in my book is: coil, alternator field, brake lights, starter. This is literally all you need to have a running daylight only car.

The harness is pretty much all one piece in the 914, which is typical of cars of this era. It runs from the right front light to the left front light down the left bottom of the trunk, below the fuel tank, up to the scuttle (below the windscreen, cheating right to pick up the wipers, front blower, and fuel sender), and down through the scuttle to the driver's footwell near the fusebox. It splits here to the fusebox, the dash, and across the front firewall behind the pedals (picks up the brake switch) and down the center tunnel. After passing through the rear firewall, it turns up and splits again, with several large gauge (10 and 12 gauge) red wires to the battery, and the rest over to the left side to split again to a large ground point, the relay board, and the rear trunk. The relay board splits the wiring to the engine harness (coil, sensors, rear blower). The rear trunk harness runs along the left side to the left rear light, then the right rear light (hitting the license plate lights along the way).

In my view, there should really be five sections: the front, the dash, the engine, the rear, and the tunnel section.

If you disconnect and completely remove the fusebox, and disconnect all of the wires from the switches, you can pull the wiring through the scuttle grommet into the front trunk. Some of the dash to fusebox wires will also now simply be loose. The rest will connect to the tunnel section. You'll also notice there's a junction in the driver footwell joining some large red wires from the tunnel (from the battery + post) to a lot of smaller red wires to divide up the power. Remove all but tunnel red wires, and two of the smaller red wires from this junction. Here's your primary power source.

Connect one red wire (small is OK, like 18g) to the ignition switch. Connect the other to a 30amp relay, which will provide the switched +12. Connect the switched terminal from the ignition switch to the relay switch terminal. One (brown) ground wire off the relay, then the remaining connection is the primary switched power source. This will connect to many things eventually. For now, using a small bolt, nut, and a pair of insulating washers to connect it to someplace on the body, with the free end of the bolt past the nut pointing out at some convenient angle. Use ring terminals on this bolt with a second nut to split the switched power to the black wire on the tunnel section, one terminal on the brake light switch, and one terminal on the G light in the combo gauge.

The blue wire in the tunnel section needs to connect to other terminal on the G light. This light is required to make the charging system work. The engine bay end of the blue wire connects to the D+ terminal on the voltage regulator. This normally connects to a pin on the relay board, which then connects both to the D+ terminal on the VR and the alternator. You can do this if your relay board is intact, or just plug the VR directly into the plug off the alternator, and splice into the red wire. Finally, you can simply connect it to the D+ post on the alternator with a ring terminal, along with the red wire to the VR. If you need to remake this bit of wiring, the red D+ connects to D+, DF to DF, and D- to D- (red, black, brown).

The brake light switch should connect to the black/yellow wire in the tunnel section. This should go all the way back to the left taillight housing, and daisy chain to the right taillight housing.

The final wire you'll need is to connect the yellow wire from the tunnel section to the starter terminal on the ignition switch. This simply goes back and connects to the spade terminal on the starter solenoid (it goes through the relay board stock).

From the battery + post, there are two large wires that go into the center tunnel, and one very large wire that goes through the rear tin, over the gearbox, and connects to the starter solenoid. If this isn't intact, you'll need to make something like this. You can use one 12g wire from + through the tunnel to our relay, but the wire from the + post to the starter needs to be pretty large, like 4g. You can also run the 4g wire ONLY from the + post to the starter, then run the 12g wire with a ring off the same post on the starter forward through the tin, using same hole as the yellow starter wire.

With all of this hooked up, and the - strap on the battery, and a ground strap from the transmission to the bottom of the trunk (above the tail cover on the transaxle), the car should start and run if you have carbs. The brake lights should work, the G light should work, so you should see 13.5 to 14.5v at the battery terminals with the engine running.

If you have EFI, there's quite a bit more wiring to do, enough that finding a new all-white harness (if yours has been destroyed) for the ECU would be a very good idea. I'll fully describe wiring for EFI in a later post. It will likely be for aftermarket EFI, but much of it should be relavent to D-jet, too.