On my 1999 Savana GMC 2500: While on jacks, my rear wheels did no stop when I applied the brake. Chevy told me my ABS needed to be replaced. I went to the Junk yard, got a $100 module and installed it. My first problem now, is that I had marked my lines, but the markings go covered in grease and I couldn't read them. I'm 90% sure I put them back in the right places. Is there a way to check this? After installing the ABS module, bleeding the brakes, the problem is exactly the same: I can't stop the rear wheels from turning at idle. I don't see a proportional valve. Is that done in the ABS?

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    Welcome to Motor Vehicle Maintenance & Repair! Have you looked at the brakes themselves? Is there meat left on the shoes? If so, have you tried to adjust them? You can also check to ensure you have movement of the rear wheel cylinders when you apply the brakes (takes two people: one to press the brakes; one to view what's going on). I would bet adjustment is all you need to do here (if you don't need to replace the shoes). – Pᴀᴜʟsᴛᴇʀ2 Jan 1 '18 at 18:37
  • Another thought: Does the parking brake work? – Pᴀᴜʟsᴛᴇʀ2 Jan 1 '18 at 23:17
  • If you have the rear jacked up at the body, and the rear wheels are hanging down, thinking it is in an extreme braking situation, the wheels may still be moving itbecause the proportioning valve is working properly. If jacked up at the differential it should stop the wheels. – X-tech2 Jan 4 '18 at 3:46

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