1999 Ram 2500 has the brake and abs lights on and the speedometer isn't working properly.

SOURCE: abs brake lights come on and stay on

Replace the speed sensor in the rear end.

SOURCE: 1999 Dodge Durango. Brake Light and the ABS Light

If you backup lights are not working as well, I would say check the fuse for the backup lights, if the fuse is good, see if you are getting power to that fuse. We had this problem and after weeks of searching and changing sensors, we found the backup light fuse was good, but not getting power. Ran a wire from that fuse to the cig. lighter fuse and all woprksf great.

SOURCE: dodge 2500 ram diesel no tail lights and my abs

replaced the IPM (the fuse box) it was shorted

SOURCE: 2004 Dodge Ram 1500

i just had the same problem w/ my 04 ram.......after replacing the sensors that the abs computer codes gave me it still had the same problem....then i unplugged the abs module only to find water in it.....apparently its a problem w/ dodge.....i dried it out with an air hose and it works fine now... hope this helps.......Chip

SOURCE: etON 1999 Dodge Ram 2500

there is an ABS sensor on top of the rear axle, and they are known to cause these symptoms-check the wiring, connector, and replace it if necessary, they are about $30 and is held in place with one bolt.