my truck has both the abs light and the brake light on almost constantly.sometimes when i start the truck they come on instantly and sometimes after a short while, often after i hit a bump.the lights always come on together and never go off until i turn the truck off. sometimes i can turn the truck off and restart it and the lights will stay off.the truck stops fine under normal breaking but the abs(truck has rear abs only) shuts itself off when the light comes on.this is a 4x4 truck with a tortion bar crank so it rides rough and has been coverd in mud alot. i was thinking this is a lose connection somewhere in the abs wiring. can any1 help? i hav been driving like this for months cuz im broke&it still stops fine.

 

i had that same problem when i first bought my truck so i went and asked the dealer and they told me to add alittle break fluid so i did and the lights havent came on sense

 

ever change ur brake fluid... bleed ur brakes??

 

i hav checked the brake fluid often, and to my knowledge it has always been full. i have never bled the brakes cuz the truck stops fine, has a firm feel, and dosnt ever fade. is there something i dont kno?

 

check the speed sensor on top of the rear diff.

 

how do i tell if the speed sensor is bad? i mean i kno obvious damage but how can i troubleshoot that thng?

 

Remove the speed sensor and make sure that you don't have a big bundle of copper wire inside your diff. The only way you can troubleshoot the sensor without any obvious damage is stick a piece of metal on the end (the end is a magnet) and check to see if you have continuity between the 1st and 3rd terminal of the sensor. You should have continuity with the metal on the end and it should go away when you take the metal piece off. If not, replace it