the connector you are looking for is on the LHS of the fuse box as you lok at it in the footwell, i know this coz i had to do it on mine, the one under the carpet is on the later models. it has 4 wires on it hold on i will get you full description.
How to use the self diagnosis function on the Mk2 Rover 800--
To acces the diagnosis function for the fault codes you will need to find the right connector, the connector is under neath the dash
just above the pedals, the connector has 4 pins and is connected to a bridge connector, to make sure you have the right connector
check that there are 4 wires coming from it and that the colours are as follows--
Yellow/green
Yellow/black
Purple/slate
Black
You will need a small piece of wire (2-3 inches is fine), ensure the ignition is switched off and remove the bridge connector
(basically another connector that connects to the one you will be using) you then need to take your small piece of wire and
connect one end to the yellow and green wire in the conector, then connect the other end of the wire to the black wire in the
connector..
You should now have a wire which is connecting the yellow/green wire to the black wire in the same connector effectively shorting
the 2 wires.
Check that this is correct before switching on the ignition, the ABS warning light should now start doing its thing!
It will flash code 1-2 x three times, this will take the form of
1 flash ----a 1 second gap-----2 flashes
1 flash ----a 1 second gap-----2 flashes
1 flash ----a 1 second gap-----2 flashes
These first flashes are the systems start identification, if the lights dont flash like this first then recheck the connection on the
connector you have bridged.
After the system has carried out the start identification flashes there will be a 3 second pause before it gives you the fault codes,
these will be displayed in the same way.
For example if the fault is with the return pump then the fault code would be 3-5, this would be displayed like this
3 flashes of the ABS light------1 second gap-------5 flashes of the ABS light,
3 flashes of the ABS light------1 second gap-------5 flashes of the ABS light,
3 flashes of the ABS light------1 second gap-------5 flashes of the ABS light,
Then the sequence will start again, if you have another fault however the system will then go on to flash another code as
the system can store 3 fault codes in its memory, once the fault codes have been displayed the system will start again, always
wait after you have received the codes for the 1-2 identification code to confirm that there are no more fault codes to display.
Once you have fixed the problem that the fault codes reffered to you need to clear the codes from the system memory ( this isnt
necesary but if not done the same codes will continue to show at a later date )
To clear the codes turn off the ignition and refit the bridging connector that you removed earlier.
Then turn the ignition on and wait for the ABS warning light to extinguish (about 2 seconds)
When warning light extinguishes turn the ignition off.
This must be done 20 times (yes 20 times) to clear the ABS memory.
In my experience after clearing the codes it is a good idea to check car fuses as i have seen a few blown due to the process
of switching the ignition on and off repeatedly.
You will find the page with all the fault codes for the ABS by clicking the link above.
Fault Code
Start identification 1-2
Front left wheel solenoid valve 1-6
Front right wheel 1-7
Rear wheels solenoid valve 1-8
Relays or relay power supply 1-9
Pulser ring 2-5
Return pump 3-5
Brake light switch 3-7
Front left wheel speed sensor signal 3-9
Front left sensor continuity 4-1
Front right wheel speed sensor 4-2
signal
Front right sensor continuity 4-3
Rear left wheel speed sensor signal 4-4
Rear left sensor continuity 4-5
Rear right wheel speed sensor 4-6
signal
Rear right sensor continuity 4-7
Battery voltage too low 4-8
Electronic control unit 5-5
Interruption of fault codes 5-6