My ABS light was flashing intermittently (more on than off). I cleaned up the sensors at the front wheels with a toothbrush and the ABS was fixed ...... for a few days. We had some snow and slush and the light started flashing again when I hit bumps and then it stayed on. I just had the front wheels apart again, cleaned the sensors (with trusty toothbrush) but the light is still there.

When I looked at the ABS control module under the front seat it doesn't look like the Bentley illustration and so I am stuck on how to troubleshoot.
My Volvo experience has told me that most of my electrical problems are a corrosion issue. Where do I find the likely culprits in the ABS system?

Thanks for the help.