What could cause the ABS and brake light to come on a '99 Dodge Ram 1500 AWAB?

Answer 1

First check the fluid level if ok you need totake it to a dealer to find out what is wrong with the ABS. They set codes in the EBCM just like the engine does in the ecm and can be read with a scanner. Most parts stores con't read these codes.

Had this problem with my 1999 Ram 1500. There is a sensor at the top of the rear differential for the ABS system. That sensor went bad and replacing it took care of the problem. What caused mine to go bad was apperantly water got into the differential when launching and loading my boat. check to see if gear lube needs to be replaced also.

The answer above is perfectly correct. When the ABS sensor on the diff goes bad the speedo no longer will work, the odometer stops recording mileage and both brake and ABS light comes on. You also loose O/D or "Lock-up" in the torque converter. The sensor is inexpensive and can be changed in about 30 mins. Good Luck!

I second the second answer :) My ABS light was on, my BRAKE light was on, my CHECK ENGINE light was on, my SPEEDOMETER wouldn't work below 35 mph, then quit working alltogether. Once the speedomenter quit working the odometer and cruise control quit working. I replaced the rear differential mounted speed sensor ($33) and then reset the CHECK ENGINE light by disconnecting the positive battery cable for a couple of minutes. EVERYTHING then worked.

Replace rear differential speed sensor as follows:

a) remove parking brake cable bracket (1/2" socket)

b) remove speed sensor bolt (9/16" deep socket)

c) remove metal speed sensor cover

d) remove speed sensor from rear differential housing (use channel lock pliers, twist gently back and forth while applying upward pressure. Once the speed sensor has a small gap between it and the rear differential housing, insert a flat-blade screwdriver and gently apply upward pressure while gently twisting speed sensor back and forth.

e) disconnect speed sensor from speed sensor cable

f) lubricate new sensor with WD-40, insert into rear differential housing. It will NOT go in all the way by hand, so do NOT force it nor hit it with anything made out of metal.

g) replace metal speed sensor cover

h) Insert speed sensor bolt and tighten LIGHTLY until a small amout of pressure is felt. Tap speed sensor with rubber hammer until it pops into housing. Finish tightening of speed sensor bolt.

i) replace brake cable bracket, replace 1/2" nut and tighten

j) disconnect positive battery cable for 2 minutes, reconnect positive battery cable

h) start vehicle, enjoy, brag to wife and friends.