Recently I was driving on the freeway and had to lock up the brakes on my 99 Ram 2500 4x4 because of an idiot big rig driver who decided not to look and run me off the road. About thirty seconds later my speedo starts acting up and dropping then goes out and my brake/abs lights and engine check light all come on. I know I have a bad map sensor too but I already have a new one to replace it with. About fifteen minutes later, at about 80mph, the speedo comes back. Over the next few day the brake/abs lights come on intermitently and the speedo would go out on it's own and just the other day the speedo completely fails and the brake/abs lights are now permanently on. Also I have a bad left rear blinker/brake light that I'll start with today.

Also yesterday, my tranny automatically shifted out of OD on it's own. Both times it happened about five minutes after being on the freeway.

Any help wopuld be greatly appreciated

 

Usually when you get the Brake/ABS light and you speedometer is intermittent, it's the rear wheel speed sensor that is the culprit. It's about a $20 part and doesn't take but 10mn to replace. I would start with that and see what happens.
Good luck.
mishkaya

 

Rear wheel speed sensor. $41 at the dealer. Takes 10 minutes to change.

 

Thanks guys. I'll try and locate one today.

 

The above advice is sound in my opinion, but there is something else in your story that I want to point out. When you made the panic stop, you might have caused the stoplight switch to over extend. When they are installed they are adjusted to each individual application. It could be causing part of your problem. They run about $12 at Auto Zone. If after you replace the sensor you still have an ABS light problem, you might want to look in that direction.