Rear ABS Light on at 35-40 MPH

[ssevans]

I have a 1990 Ranger 2.9 L the rear anti lock brake light comes on between 35 & 40 MPH and stays on until you turn of the ignition the in again between 35 & 40 MPH, I have done a complete from and rear break job, replace the rear speed sensor, the vacuum booster, master cylinder the rear control valve, and have blead the system, but still have the same problem. there are no codes and the system checks normal when scanned. Does anyone have any ideas?

 

[pcollins]

The tooth ring in the differential? not sure. My ABS system is messed to. i just took apart the dash and took out the bulb. I don't need ABS..

 

[ssevans]

That is my last guess, I was hoping there was something simple I might of missed but it is looking more and more like the exciter ring, Thanks for the input