Disco Gems into a Defender wiring harness

Cabin/main loom side you will need the orange /grey plugs that engine side plugs into with as much pigtail as you can. The fuel pump relay & related wiring are part of the loom. Between the fuel pump relay and the wire out to fuel pump is the inertia switch which breaks power to the pump @ all the wrong moments. You’ll also need the obd2 port from inside under the fuse box.
Color on those plugs changed from 96/97 to the the 98/99’s. The color change on plugs corresponds to the switch to advanced evap system. There is a black plug with all heavy gauge wires again as long a pigtail as possible.
I delete the inertia switch on our personal trucks.
There is a diagram posted here on the site explaining the wire colors and what goes to what in order to make it run.
On the transmission loom I cut it up high behind the engine. I don’t use anything but the reverse lamp wiring and remove the interlock solenoid on the tcase. We use Lokar shifters so it comes up through the defender shift boot & looks like a manual shifter. If you intend to use the d1 shifter you may want to retain more. Be sure not to cut the o2 sensor plugs that are part of the engine loom but run over top of the transmission.
FWIW we’ve tried ecu’s where alarm hasn’t been programmed out and truck starts.
If you text me tomorrow I’ll shoot you some pics. Building my daughter a 110 5door with the drivetrain from the d1 she rolled. Have it up & running beautifully.

This is a popular swap, but getting the fuel injection system wired and running is the easy part. The fuel injection ECU needs a speed sensor signal, otherwise you will likely experience stalling at low speeds, especially if you have AC. This isn't as simple as running a wire from the speed sensor to the fuel injection ECU as the signal changes before it gets to the ECU.

If you want everything to function correctly, you'll also need a fuel tank with a proper vapor dome so that you can run the charcoal canister and not have fuel vapors venting to the atmosphere (if not for the environment, then for fuel odors). If you use a later non vented fuel cap (the smaller one with the plastic filler neck) you'll have fuel tank pressure issues as the fuel level drops creating negative pressure in the tank or high pressure as the fuel temp increases.

As Robertf stated, some ECUs will not flag a check engine light if the ABS is not connected, but it will still log a fault. I think we have a solution for this, but haven't tested it yet.

this one, not the disco vss.