A very big thankyou to Maverick for this info:
I can only assume that the wire Maverick talks about is what the ECU/ABS uses to stop the ABS activating at below 10mph or whatever it is. I tested my ABS by jumping on the brakes and it still works. Everything else is still working too. My idle is absolutely rock solid at about 800rpm with and without the aircon compressor on. The low speed driving, like in traffic jams, is so smooth now. No lurching or jumping as the car tries to rev.
I love Maverick (in a buddy slap on the back type of way of course
Normally while you are moving with the clutch in the idle in the alfa should stay at 1200rpm and drop to normal when stationery, the little trick removes the 1200rpm bit.
When the car was stationery the idle was rock solid.
When the car was moving with the clutch in it bounced between 500 and 1500 rpm, this was regardless of cars actual speed. By that i mean i could put clutch in at 70mph and let it return to idle and it would keep bouncing until the car stopped moving. I found it very dodgy approaching junctions.
DONT DISCONNECT THE PLUGS FROM SPEEDO BECAUSE YOU RISK THE AIRBAG LIGHT COMING ON AND IT WILL COST TO GET IT RESET.
On the back of the speedo there are 2 plugs A & B
ABS sends signal to pin 11 of connector A on the back of speedo.
This in turn is sent out on pin 15 of same connector to the ECU and also from pin 16 for the aircon.
I cut the wire coming from pin 15 and now my idle just settles to normal idle speed with no bouncing, except for 1 little dip with the aircon on and then it goes straight to normal idle and stays.