Fiat 500 ABS

[Mr Jenks]

Hi all, A good friend has asked if I could look at his daughters Fiat500 starting problem. I reckon that`s sorted but when they left it with me the ABS light was on. I know it comes on when switching ignition on, does its self test and goes off, then comes back on immediately. Suspect a wheel speed sensor, but can anyone send a wiring diagram for the ABS so as I can see whats going on, even a pinout from the ecu would do. Thanks,