Found a link I referred to when installing mine. I was wrong about using road speed sensor wire for winching, it is auto box neutral / air con wires.
So here's a copy and paste:
You should have a single 7 or 9 pin connector that doesn't have a home. The wires that come to this will be as follows...
Brown, white/slate, white/purple, black/yellow, black/orange, yellow, yellow/blue, brown/purple.
Some secondary colours vary with different model years and markets, but the basics will be the same.
The main connections are as follows...
Brown to main battery supply - permanently live.
White/slate to ignition switch for the 'ign on' signal.
White/purple feeds power to the fuel pump, but ensure that this then goes through an inertia swicth for safety.
The above are the main functions that apply to this connector. The others there are for ancillary functions as follows...
Black/yellow is the feed wire from the ECU to the dash warning light for EFi faults. Not an essential fit.
Yellow is the sensor wire to the ECU from the road speed input sensor. This assists the correct implementation of the idle speed, but is not that much of an issue if not fitted. However if the sensor IS fitted then the standard inbuilt speed limiter in the ECU will be active and kill the fuelling at between 110 and 112mph.
Black/orange is the sensor wire from the auto gearbox to indicate when the gearbox is in neutral and so the load on the engine is less. This is to enhance idle speed control and with a manual box is superflous.
Yellow/blus is the sensor wire from the air conditioning unit and again is an idle speed control function to ensure idle speed is maintained high enough when the aircon loads the engine and drags speed down. Not used unless your car retains aircon.
Both these latter two functions can be reallocated to other very heavy load functions that can drag the idle speed down and risk stalling.
Brown/purple is a function not used in the UK, but is going to be an additional sensor function for idle speed control.
In addition to the wires in this plug you will find a number of other connections. There are several separate earth connections. The ones nearest the injector end of the loom are intended to be bolted to the engine and not the body of the car. This is to allow for potential poorer earth paths from engine to body later in life. There will be additional earths nearest to the ECU plug end.
There are also a couple of standard relay holders which are for the main system relay and the fuel pump relay. You can see the colour codes of the wires from what I mention above.
A very important single wire connection that is separate and found near to the airflow meter plug is a single white/black wire which is the sensor connection wire for the negative side of the coil. This provides the ECU with engine speed information and has to be connected to the ECU through a 6.8k ohm resistor. This should actually be in the loom so a simple resistance check from the end of this wire to the ECU plug, pin 39 will reveal whether the resistor is in circuit. If not get one and use it to protect the ECU from spikes.
There will also be another couple of connectors. One should have a sealed resistor in it and is known as the 'tune resistor'. This alters the actual map in the ECU that is used.
There is also a diagnostic plug that should have four wires. Black/slate, white/light green, white/pink and white/yellow. Leave this untouched as it will alow for any Rover diagnostic unit to be plugged in and system faults read. Very useful if you have a problem that you can't get to the bottom of.
