Hi, new to this forum. After sitting for six months, I put the 03 3500 diesel back on the road. It needed new batteries. I changed them. Once I got it started, the abs and brake lights are on all the time. I changed the rear abs sensor that's in the diff...lights still on and no abs. Maybe the front ones? If so, easy to change? Is there a fuse that could be looked at? Any help appreciated...Thank-you!!

 

If I had to guess other than wiring it would be a wheel hub, or wheel bearing.

 

the sensor in the brake fluid reservoir?
low brake fluid? im sure you have checked these.
maybe try to pull a DTC off the computer?