Front wheels locking and unlocking after Ashcroft ATB installation


Well-known member
Nov 16, 2007
Houston, TX
2003 Discovery has never had 3 Amigos issues. Recently had Ashcroft ATBs installed front and rear. After, 3 amigos and brake warning light were on but vehicle drove fine. Using a Hawkeye Code reader, when I try to test the ABS system I get a couple of errors; 4044 Sensor RHF. Also Air Gap Too large. Code 4084 Sensor RHF intermittent sensor output and "broken wire."

When I check the valves either front left or front right, wheels rapidly alternate between being locked and free. Ran a test on the shuttle valve and it came back fine. I have the WABCO replacement but haven't installed it yet. Before deferring to shop, I want to replace the ABS right hand front sensor. Does this seem like a good plan? I can get a new one for $119 plus shipping but will have to splice the wiring. Would appreciate being directed to a video or something as I'm having trouble visualizing this. I feel confident the shop likely accidently damaged the sensor but if I can repair it and save the headache of dealing with them, I would like to. Thoughts? Recommendations?



Well-known member
Oct 29, 2004
St. Louis
There’s some info on the ABS modulator fix/shuttle bypass procedure. May be worth looking at. But also sounds like a wheel speed sensor & tone ring issue. Like the sensors aren’t reading correctly so the abs keeps locking alternate sides to correct the bad reading.

When I upgraded my axle shafts to HD, the front CV’s don’t have tone rings. So my first drive on the highway, I hit the brakes at about 65mph and the ABS system freaked out and started locking different wheels. I nearly rolled my truck.

That may not be what your problem is, but it’s a good story to share!