I just bought a 97 Accord EX 5-speed 4-cyl w/ leather. It's in great condition with one exception- the ABS is acting up.

The car seems to be in one of two states

About 1/3 of the time the ABS is actually functional, there is no ABS light lit up on the dash, but there is a black cylinder looking thing on the driver's side of the engine bay that makes a loud mechanical sound so loud that you can hear it and even feel it sometimes inside the car... it even makes the RPMs drop to the point you think it might die if the car is in neutral. It does this usually only when the brake pedal is depressed and does it between every 10 and 45 seconds.

The other 2/3 of the time the ABS light on the dash is on, the noise I described above doesn't occur, and I'm going to guess that the ABS wouldn't work if I tried it out.

It seems to be more commonly (but not always) in the first state (with the noise and no light on the dash) when I first start the car up, and more commonly in the second state after it has been running for 5-10 minutes or so.

I'm going to guess that the black cylinder shaped module in the engine bay is the ABS control module.

So what do I need to do to fix this? Can I do it myself (I'm a decent shade-tree mechanic)? Where can I get the parts the cheapest?

I have a pic of the module thats making the noise/vibrating that I took with my phone if anybody needs to see it... I'll have to wait until I get home though so I can sync it w/ my laptop.