The ABS light on My wife's 2000 EB Expedition (62K miles) came on yesterday. I seached on Yahoo [Ford and Expedition and "ABS light"] which led me here.

I changed her rear-differential speed sensor with the one from my 2001 F-150 SuperCrew and it fixed the problem! Although I now have the same problem on my SuperCrew until I can get a replacement.

Thanks for all the help and maybe this will help someone else.

Details:
I found that when you turn the key to run position, the ABS light comes on with all the other lights, then goes out, you hear a quick vibration form the ABS Module (near the master cylinder), and the light comes back on and stays on.

The quick vibration is apparantly the ABS self test during initial startup. If you hold your foot on the brake while turning the key to run, the ABS light will not come on until you release the brake. Apparently, the self test does not happen until you release the break pedal.

First I cleaned the wheel sensors on the front rotors; they were filthy, but that didn't solve my problem. Then I went to AutoZone to buy a rear-diff. speed sensor; they didn't have it so I bought a Haynes manual instead. It talked about the brake-light on/off (BOO) switch. I disconnected the BOO and the ABS light did not come on! I thought I was on to something so I tested the switch and it was working perfectly.

The only thing I had left before going to the dealer was to replace speed sensor and that saved me the trip and the bill! I guess when it didn't get a reading from the speed sensor during self test, it disabled the system and gave the warning light.

Thanks everybody!

 

I had the same problem.....ABS light came on when I started my 2000 F150 and stayed on all the time. I changed the speed sensor on the rear differential and the light went away and the ABS system works again. Sensor cost $18.33 + tax, sure beats taking it to the dealer! Thanks for the info, it saved me big $$$, hope this helps others do the same.