It's a small daughter board. It actually looks like one of those PCB's that's created using a printing process rather than traditional etching or maybe the plastic overtop of it just makes it look that way. It could possibly have an accel sensor or gyro sensor on it. I notice there's another one at a right angle to it on the left. Seems like a lot of connector pins for a simple sensor, though.
How advanced is the ABS module? Usually they are pretty simple, they take the 4 wheel speed sensors, when they detect a wheel stuck, they just start pulsing the brakes. I haven't really been following this stuff lately, since most of the amateur race cars are all pretty old, but it's quite possible they've added accelerometer data into the mix.
If you can get a part number off of the chip in there you might be able to look it up.
It seems pretty basic.. it's from 1995 from a Subaru legacy
the funny thing is I've been googling part numbers and I have yet to get a hit on anything... I did something as simple as the two main IC's as you see in the foreground.. no hits at all
A lot of proprietary parts in these things. Many times the parts are exactly the same as something else that is sold in regular retail or only slightly off, but the part number is specific to the OEM application.