I have a 1997 discovery SE7Long story short after replacing the master cylinder and the abs modulator unit the abs light is on and no fluid makes it to the rear brake lines. Here is the full story below.

I just purchased it, and it has problems with the brakes. They don't work well at all. You have to pump them to slow down. I tried bleeding the brakes. (2 person method) Both rear lines had almost no fluid. (One line did have a few drops) The front 2 bled just fine. after getting it home I replaced the master cylinder. (thinking that it just wasn't building enough pressure) That didn't work. Then I removed the rear brake lines from the abs module 1 at a time and no fluid comes out of either hole in the module when pumping the brakes. I then noticed that the abs light doesn't come on when starting the car. I found that someone had removed the light in the dash. Also the connector on top of the brake fluid resivor only has 1 wire attached. Someone has done alot of messing around with this car. I then used a paperclip in the obd 2 port and found the following codes.
2-6 brake light switch fault or fault in wiring to switch or not connected 2-8 no voltage to abs solenoid valves, faulty valve relay or wiring 2-14 sensor failurefront left Too large an air gap, or sensor has been forced out by exciter ring – try tapping sensorback into place. 3, 3-2, 3-3, 3-5, 3-6, 3-7Solenoid valve failure. Open circuit between ecu and solenoid valve in a) modulator b) wiring harness or c) inside ecu 4-14 sensor failureFront left Wiring to sensor is broken or sensor resistance is too high. Inspect wiring at sensors. 5-14 sensor failureFront left Sensor wire has an intermittent fault – check connection(s) 6-14 sensor failureFront leftno output from sensor. Sensor may have too large an air gap. Try tapping in sensor(s), checkconnections. 4-12 Front rightWiring to sensor is broken or sensor resistance is too high. Inspect wiring at sensors
The front left sensor wire is broken open. So that explains a few codes. I then replaced the abs module with another used one. Still no fluid makes it out of the rear abs module holes.

At this point I'm totally confused. I figured the abs module had the valves going to the rear wheels stuck shut. But unless the other one I put on has the same problem something else is going on. I think there are only three things to narrow it down to at this point. The brake lines going to the abs module are clogged. The pressure reducing valve is clogged or faulty. Or the abs ecu is telling the module to close the rear lines. But I'm really in over my head. There could be something else ovious that I'm missing. Does anyone have any advice?

 

Haven't fixed abs problem yet but pressure reducing valve isn't letting fluid travel to rear brakes.

 

similar problem happened to both my 95 and my 96 ,you can get a replacement from Wilwood ( got mine from Summit racing), easy install , just needed to make a couple new lines.
and a word to the wise.....while you are working on the brakes...remove the pads and try to pump the brakes so as to get the pistons to actually move, they may be partially seized from setting around and not working

 

I've tried to bleed the brakes several times with 2 people and fluid is coming out the back. However when I tried using the 1 person method by using a tube ran upwards then down into a bottle so no air would get in the proportioning valve closed off pressure to the rear brakes again. So with the valve still in the car I took the end off and cleaned it out to open it back up again. That worked for a second but eventually the valve closed back up yet again. Do I need a new valve, or do I just need to go back to the two person method that I had no problems with?

 

Get a new F/R valve