'95 wheels lock up

So last night I took my Blazer shopping cuz my car was full. Anyway, it was raining and I hit the brakes to stop and the wheels locked up. Had I not been able to swerve around the guy in front of me, I would have rear ended him big time. I have 4 wheel anti-lock brakes, but the anti-lock brake light in the dash is on so I know I have to pump the brakes myself. (The ABS hasn't worked in the 18 months since I bought it.) I tried the brakes about a mile later and they locked up again. I've only experienced this phenomenom one or two other times since I bought the truck. Is there a proportioning valve between the front and rear brakes that works independent of the ABS that I can check? Any ideas?

Solve the ABS problem, and it won't do that any more. The system is called "Anti-LOCK Braking" for a reason. The bias from front to rear is terrible, and the ABS control and modulator are required to function to prevent lockup.

I didn't want to spend ~$500 on a new ABS module.

You could install an adjustable proportioning valve, but that might not even help. Has it been diagnosed? Are you sure it's the module and not the modulator?

I didn't want to spend ~$500 on a new ABS module.

Then don't complain about us about the antilock brake system not working and the braking being poor when you know what the problem is.

The whole brake system runs through the ABS valving so without the ABS working your brakes will not work the same as a standard brake equipped vehicle.