The PMV is the Pressure Modulator Valve. Like I mentioned, it'* right below your airbox. It has a good bunch of brake lines coming and going (6 total?), and a small reservior on it if you have traction control on the car from the factory.
New, they're about $700. From the wrecker they'll probably be $150 or so, and many GM cars used the same unit. Your wrecker will know the cross-model compatibility.
However, since both systems seemed to fail at the same time, I'd suspect a wheel speed sensor.
Get the car up in the air, and check the connections to all 4 hubs. You'll see the connectors. disconnect each one, clean them up, and apply dielectric grease before reconnecting.
You might also want to pressure wash the back of the hubs if you have one available.
You might get off easy on this one.
A faulty WSS might be detected with an ANALOG voltmeter set for resistance, so you can see the 'pulses' on the needle as the tires rotate. You'll need a helper for this.