Ok, so maybe I should have checked the FAQ first. Would anyone be aware of other reasons for the pulsing? Thanks

ABS Pulses at Low Speeds. [Query:] The ABS acts up when I'm driving at low speeds and applying hardly any pressure to the brake pedal of my 1990 740 GLE. The ABS lifts the brake pedal in the same way as if it was locking up. [Response:] You should remove and clean the front wheel speed sensors. To do this turn wheel full lock to one side and then remove the sensor from wheel that is turned out by undoing a 5 mm Allen screw you will see adjacent to arm where tie rod for steering attaches. Then turn wheel to full lock the other way and do the same on other side. Also unplug and then reconnect the sensor connectors that are in the engine compartment near top of struts. This should effectively clean the connections. This can also cause low speed inappropriate ABS activation.
[Tip from Bob Dietz] Apparently when the waterproof connectors to the ABS sensors at the differential (rear) and shock towers (front) are molded on the sensor wire itself is under a lot of tension--I've found many of these with only one or two strands of wire left unbroken, even though the insulation looks fine. This can cause lost ABS signals. Volvo can supply replacement pigtails. It's a piece of white wire with the identical end molded on. I line splice and solder the joint, shrink tube over. Try to maintain the twist. All the signal cables for ABS are twisted pair. There is also the possibility of signal loss through non-waterproofed connectors.