my abs and brake light has been on since i bought the truck and after doing some reading i figured that it might be the rear sensor, so when I was at autozone ( or the twilight zone depends on who's working) I picked up a rear speed sensor. Then, i heard if the speedo is working (mine was), probably not the rear so i didn't install it figuring maybe i'll stop by my friend shop and use the snapon scanner that can read abs codes when I get a chance. Today I put the back axle up on some stands and pointed it away from the house and ran it in 6th gear, because i'am trying to isolate a 60-70mph heavy vibration and guest what no speedo. So, with the truck already in the air and the sensor on the front seat I gave it a shot. No light! Back to diagnosing the vibration.

You have 2 sensors one in the rear end and the other on the side of the tranny.

Actually, I one in the diff, and one on each front wheel. The only sensor that I can see on the tranny is the reverse switch. Early I checked to see by pulling the plug with the tranny in reverse and the reverse lght went out.

Yeah... 4 wheel Antilock brakes have 2 front axle sensors and 1 rear axle sensor... So if you got the light out now you doing good... Now deal with your vibration problem... U Joints?Carrier Bearing?Out of balanced driveshaft(s)?Out of balanced tires?

I believe it's an out of round tire on the rear--well one is a little out of round. I didn't pull the driveshaft, but i watch it with the rear tires off the ground at about 60 mph. Then i used a large belt wrench on the drive shaft with the rear brakes locked and tranny in N then again w/ the tranny in R with rear brakes unlocked and didn't see any play. If I have to get a new tire(s), I may try balancing all of them with balancing beads. Has anyone have any luck with them?

You may have to have the tires rebalanced. If you do have this done, make sure to watch the tire while it is on the balancer and look closely for a broken belt. The broken belt will look like a small hump in the tire. This is what happened to me when I had a vibration that I could not find. I bought new tires and this fixed the problem.

One of the tires had a hump probably about an 1/8" or better and went quickly from low to high to low. I noticed it by running in 2nd at idle with the rear wheels up.I'd imaging thats probably enough to do it.

You have 2 sensors one in the rear end and the other on the side of the tranny.

I was thinking vss, The 0500.

One of the tires had a hump probably about an 1/8" or better and went quickly from low to high to low. I noticed it by running in 2nd at idle with the rear wheels up. I'd imaging thats probably enough to do it.

That is enough to make the vibration that you are talking about. Try changing it with the spare and see if the vibration goes away. If it does, then you need a new tire.