The ECU requires a variety of connections. As a bare minimum they are:
12V – Switched power. There is a 7.5A fuse in an inline holder. The unit is rated for 6A.
Ground – Obvious.
ZF Mainplug – This goes to the autobox to drive the solenoids and things.
Disco 2 XYZ Switch – This tells the ECU the position of the shifter, and also has additional connections to switch the reverse light and a starter interlock to stop the engine being started in any gear other than Neutral (Park is included, it’s essentially Neutral with a locking pin holding the transmission in place).
Oil Temperature Sensor – The ECU changes parameters based on oil temperature.
Throttle Position Sensor – It uses this to estimate engine torque so it can work things out.
MAP Sensor – Similarly it can be used to work things out.
I’ve chosen to try and keep wiring as factory as possible, and everything reversible. This to me means no cutting, splicing or soldering factory wires. I’ve also modified the Compushift loom so it’s a lot neater and cables break out in the right place, rather than them being a bit everywhere.
For 12V I’ve decided to take power from Fuse 11 – ABS ECU, which I don’t have. I’ll replace the 10A fuse with a 7.5A one so it’s protected as well as possible.
Ground will come from the ground lug on the back of the LT230.
ZF Mainplug – Goes to the gearbox.
The Disco 2 XYZ switch becomes interesting if you want to do things properly. The wires going to the Compushift I’ve crimped directly onto the ECU loom, rather than splicing the cut cable from the disco 2 loom and having yet another random connector in the vehicle. The Reversing light pins I’ve wired into an AMP Econoseal plug which is the factory plug for a R380 reverse lamp switch, so this will be plug and play. The last 2 wires for the low voltage starter interlock need to run to the starter relay in the passenger fuse box. I’m still working out the best way to get this there, however I need to put it in series with the Ground wire (which actually goes to the 10AS alarm module).
Oil Temperature Sensor is plumbed into the gearbox housing and up the main loom.
Throttle Position Sensor & MAP Sensor are both fed to the ECU, so I plan on picking them up there instead of running all the way to the sensors.
On top of this stuff which is required for the Compushift to work, I have also chosen to fit a shift interlock. These were normally only fitted to NAS and JAP spec Disco 2 autos. There’s a solenoid that gets activated when the ignition is on and the brake pedal is depressed. What this means is that unless the vehicle is switched on and your foot is on the brake, you won’t be able to take it out of Park/Neutral.
Cabling has been ordered to finish the loom.