So this was fixed under warranty by the dealership the first time it came on. This time it's not under warranty and there is no way I'm going to spend 2-3k to fix it.

The symptoms are this:
- P1590 is on and is solid. When I clear it, it comes back as soon as I start the engine - even before I touch the brakes.
- The ABS system is completely disabled; it is not operating.
- There are no other fault codes on and cruise control is functional.

The vehicle is:
- 2004 Land Rover Discovery SE7 with 80k miles. It does not have SLABS.

After reading quite a bit of conjecture about this, I am assuming that the wheel the speed sensor has failed. Does that sound like an accurate guess? Where is this thing located? If this is the problem, will the lights clear when I change this part (and I reset the codes with my hand-held code reader)?

 

Parts replaced under warrenty are covered for 12 moths or 12,000 miles, labor is not covered. So if your warrenty expired 6 months ago and you have driven less than the 12k they must cover you. Parts only. IF the same parts failed.
And yes, once you replace the failed part the light sould shut off.
They wheel speed sensors are located on the hub, they get their reading from the brake rotor.

 

Unless your hand held code reader is a Testbook (or similar multi-thousand dollar reader) you can't read or clear ABS codes. Only a dealer or well equipped indy shop can read the ABS codes, and determine what is the fault. I've had intermittent shuttle valves and ABS sensor faults. The sensor is inside the hub, and has been updated so it's hardwired directly to the ECU. Just the sensor an labor was about $500. Adding the shuttle valve kit added another $800 to the bill.

 

Since I was unable to determine which speed control sensor it was, I dropped it off at a shop and they identified the right rear sensor as being bad. They quoted me $350 to fix it and that seemed like a pretty good deal. I will let everybody know if that fixes the issue. Thanks for the help.

 

What is the shuttle valve kit? Is it something that needs to be added or just a nicety?

 

Sorry it's the ABS modulator valve kit, not to be confused with the ABS modulator shuttle valve repair kit. The shuttle valve repair kit isn't worth buying because it won't fix your problem. I had faults for both the sensor and shuttle valve. The sensor was replaced first, but the 3 amigos didn't go away, so the modulator kit was used. It used to be the entire modulator had to be replaced for $2K so $800 isn't too bad. Usually you need to replace the ABS modulator valve kit, but it'll depend on the codes you have.