Help with braking system

I have a 93 Astro, 2wd, abs.

ABS light and Brake light came on. I know that the rear brakes are not working as the do not lock up on ice. I think it is the proportion valve, but is sells for $1600. (Valve, master cylinder, and computer module)

Is there any way of testing this beside taking it to the dealer???

Morrell

If you have an autoparts store, like an autozone, that will pull the abs trouble code for you, it'll pinpoint your problem. Even if you only have rear wheel abs, like my old '89, the fact that the rear wheels are not locking up on ice leads me to believe the abs is working back there. If they did lock up on ice, the abs is definitely not working at the rear wheels.
The problem may not be with the proportion valve, it may be a speed sensor at one of the wheels. There's a fifth speed sensor in the transmission tail housing, but your speedometer would be malfunctioning as well if this one went out.
The speed sensors can be tested with a $20 multimeter by measuring the resistance through them. Getting the trouble code, a $25 Haynes repair manual and an inexpensive multimeter is a lot cheaper than a parts replacement approach.
Autozone.com has testing information on the speed sensors for your year model. Here's a link: http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/11/ad/c7/0900823d8011adc7.jsp
Cut 'n paste this into your browser and hit the enter key.

If you have an autoparts store, like an autozone, that will pull the abs trouble code for you, it'll pinpoint your problem. Even if you only have rear wheel abs, like my old '89, the fact that the rear wheels are not locking up on ice leads me to believe the abs is working back there. If they did lock up on ice, the abs is definitely not working at the rear wheels.
The problem may not be with the proportion valve, it may be a speed sensor at one of the wheels. There's a fifth speed sensor in the transmission tail housing, but your speedometer would be malfunctioning as well if this one went out.
The speed sensors can be tested with a $20 multimeter by measuring the resistance through them. Getting the trouble code, a $25 Haynes repair manual and an inexpensive multimeter is a lot cheaper than a parts replacement approach.
Autozone.com has testing information on the speed sensors for your year model. Here's a link: http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/11/ad/c7/0900823d8011adc7.jsp
Cut 'n paste this into your browser and hit the enter key.
Good info, but autozone cannot scan for abs problems, a full function scan with an abs function scanner can look at comparative wheel speed inputs and pinpoint if a wheel sensor is bad and which one.