my brake light and abs light came on the other day and I cant get it to go off for nothing. My proportioning valve was leaking and I replaced it and they went away for about half a day then came back. They are not on when you crank the truck just after you hit about 40 mph or press the brakes real hard. Any ideas?

 

Sensor on top of rear axle most likely. Also make sure the brake line running along side the gas tank is not leaking.

 

ok ill check thanks

 

Just went through this on mine. Brake and abs light were on with no other symptoms. Eventually my speedo quit working until i passed roughly 20mph then it would jump up. Speed sensor on the rear axle like stated. Roughly a $30 part and an easy change.

I'd check the brake line too, but when mine went that was noticeable as my brakes would lock up and such. Either way a common failure.

 

Rob59, did your speedo work and then quit as time went on? My abs and brake light are on, my brake peddle chatters on stopping, but my speedo works. I am trying to determine if the speed sensor on the diff. progressivly gets worse does the speedo starts to act up.
Thanks,
john

 

Yes initially my speedo worked. It didn't take too long for my speedo to start acting up after the lights came on, though. Maybe 100-200 miles later, if that. I'm sure it would have progressed to not working altogether but i fixed it before it got to that. Have a friend with a 2500 2nd gen, his speed sensor went too with the speedo progressively getting worse until his quit completely.

However, i never had an issue with my brake pedal "chattering" aside from the lights being on and the speedo eventually acting up, i had zero symptoms. The brakes worked flawlessly. If your brakes are not working properly first thing i'd do is check the brake fluid. Also, it doing it when you press the brakes hard also suggests a possible leak. I'm betting you have a leaking brake line most likely by the gas tank as that is a common issue as zman suggested.

 

A couple weeks ago I checked the fluid, it was low, but not more than a couple teaspoons. The only thing that looks suspicios is the valve body under the resiviour ( the seperate aluminum valve that has brake lines coming in and out and it has a wire attached) The front has a rubber plug and the back has a rusty, what others call a pressure valve, in it that was damp with brake fluid. I checked the fluid again and it seems OK. One brake guy said the valve is OK to be damp with fluid because it is a pressure relief. The brake tech also said the ABS would not light up if the brakes needed changed. Something is causing the ABS light to light. Someone said the brake switch, but no one really explained what happens if it goes bad. It seems by Chatter issue is unique to the symptoms.
John

 

It's most likely the sensor on the rear diff or you have a pin hole in one of the lines. Both common issues with a RAM.

 

i changed my sensor on the rear diff yesterday and did not help any. I still have the light on. I checked my lines around the gas tank and didnt see any leaks. I had my brake light switch replaced a while back I wonder if that could be the problem? Isn't there a special computer that can read those lights like engine codes?

 

Do you have RWAL? or 4WAL? If you have wires going to the front hubs, you have 4WAL, and the system gets a LOT more complicated.