Update on this: I bought the ELM327 cable and the 3 adapters off eBay last week and they arrived yesterday. I downloaded Mutli Ecu Scan and got it working with my car this morning. Error codes that came up on the ABS system was error code C1051- The reason for this fault is that ECU received invalid signal from the sensor . The fault is present now. And on the left side of the screen it says brake light switch-Off.
When I plugged just the black ELM lead in on it's own, it came up with 2 engine faults. First was fan relay 2 which was an old fault. and the second was Brake Pedal Switch and that read exactly the same error message as the ABS C1051 fault saying an invalid signal from the sensor. It says brake switch A/B match above it though.
So after that I'm assuming it's the brake pedal switch, which I'll buy now off eBay.
One other thing, what's the yellow cable do for the diagnostics on Multi Scan?