Have you definately ruled out a bad front caliper? I had a 'hot wheel' once this summer and, fearing the worst, initially suspected the ABS system itself. However, by working the pads back and forth a few times by prying them away from the disk just a little, then pushing on the brake pedal, the problem was temporarily eliminated. Then, when it was convenient, I swapped out both front calipers.

If it turns out that you also need to change the rotors, be sure to get new seals for the brake line banjo fittings. It is difficult to reinstall the old seals in such a way that they don't leak. Can you hear Gilly saying "Duhhhh"?

I found the leak doing my customary 2/3 day check after any brake job.

Also, for your information, I purchased OEM calipers and learned that there is no 'castings rebate'.

I hope your problem is of a caliper nature -- it would be much cheaper than an ABS pump or controller.