ABS and BRAKE Dash lights staying on

First check the brake fluid level. If it is low, add a little but don't fill it. If part of the master cylinder is totally empty, there is a leak that must be diagnosed. If the level is just low in the reservoir, it's time to have the disc brake pads inspected for excessive wear.

Next, find a mechanic with a scanner that can access the ABS Computer to read the stored diagnostic fault code(s). That will get you into the circuit or system with the problem, not necessarily the defective part.

Be aware that many GM cars will only store one fault code, or if there's more than one, they won't be related. Once the first problem is fixed, it can immediately set a different code for a different problem. That is more likely to happen when the original problem is ignored for a long time. That provides more time for additional problems to occur. If the light came on recently, chances are there is just one problem.

When I hook up my obd2 reader it reads ERROR. What might cause this and what is a good procedure to diagnose?

OBD2 systems started with '96 models. Cars with that system will have a second oxygen sensor after the catalytic converter.