Abs light and brake light on. Vehicle shakes 30-70 MPH?

I drive a 1996 Ford Aerostar and about a week ago my ABS light and brake light came on. They only come on for a couple seconds, right when I start up the van. Then when I'm driving and I get to speeds between 30-70 mph, the van begins to shake a lot. I checked my brake fluid and it is a little under the max. Does anyone know what could be causing this? And if I can fix it at home or will I have to take it to a shop(and how much $?) Thank you.

I think the ABS proportioning valve is going bad. If your comfortable doing brakes and bleeding them do it yourself if not don't do it and take it in

Your vehicle just need a tune up. Just take it into your local car mechanic and tell them everything and they will fix it right up. This happens often in older vehicles. The price of a tune up would probably only be around 200$. Hope for the best for you!

If your ABS and Brake instrument panel lights (the red and amber one) illuminate when you first start your vehicle, and then turns off, that's normal. At start up the vehicle does a diagnostic check and part of the check is turning on the lights so that the driver (in this case you) can make sure that they are indeed functionng.

If the lights turn on, then off, all is good. If they turn on and stay on, somethings wrong. If they don't turn on at all, that's also bad.

As far as the shake goes, that really seems like out of balance wheel(s). First inspect the wheels for anything that can unnecessarily add weight, such as dried mud. Look at the wheels from outside the vehicle, then on the other side of the wheel (this may mean getting under the vehicle.) If nothing unusual, take the wheels for balance. It's not that expensive to balance the wheel, and it can be done at most tire shops such as Wal-Mart or Sears so you can shop while waiting on the balance.

As John says, the warning lights are supposed to come on when you switch on the ignition, to prove that they work, and go off once the engine has been started.

I, too, suspect your shaking is simply a matter of wheel balance and is nothing to do with your brakes.

http://autorepair.about.com/

The lights are supposed to come on until the motor is running. You may have a bad front wheel bearing and it's causing an intermittent wheel speed sensor failure.