Is there any way to easily tell which sensor is is generating the "ABS Fault" message, armed only with a multimeter and optimism?

It generally comes on just after hitting speed bumps or potholes. I've taken the wheels off to check for a loose sensor, but they all look firmly secured (corroded) in to place.

Jack up the car and take off the road wheel. The ABS road speed sensor cable should be visible within the wheel arch. Locate the connector (usually 2-pin) and disconnect it. Behind the wheel hub should be the road speed sensor, which is bolted on and near the crown wheel.

With your meter set to ohms, connect the probes to the connector, road speed sensor side (so it measures the sensor and not the ABS system). Take note of the value with the road wheel stationary. Now rotate the wheel hub and you should observe the resistance changing. It may not be a smooth transition, but it should change.

If the resistance value does change, then the sensor is OK. If it doesn't, then you may be looking at a new sensor, or there is a broken wire in the small amount of cable form leading to the sensor.

Thanks for the advice. I did get as far as locating the plug before getting sidetracked with something or other (at 8pm on a Saturday night, how unusual!)

Now I've remembered, I shall test the sensors tomorrow!