I don't think most people realise you can actually read ABS fault codes on our cars. Well you can, just not via the ECU (i.e. via a logger). I collected most of the following information and links from searches on here (mainly Keydiver ), but it was dispersed and not clear. Hopefully this will help anyone else who's trying to track down an elusive ABS fault.
All you need is a simple voltmeter (preferably analog). First go for a short drive so the car has gone over 4mph; this allows the ABS system to complete all of it's own tests and startup diagnostics. Leave the car running whilst you read the codes. Then ground pin 1 on the diagnostic plug with the negative lead, and apply the positive lead to pin 4.
Now, read the codes according the same method used on this webpage.
Lastly, correlate any codes you get with those listed in this document: ABS Codes (you'll need Acrobat Reader).