My ABS and brake light go on and off randomly . This has been going on for 1 week , and during that time it has engaged the ABS while breaking . Small bursts of vibration . This has happened 2-3 times over the week .

I did change the rear drivers-side caliper a couple weeks ago , no other work has been done to the breaks . Other than the lights and 3 incidents , everything else feels "normal" .

Where should I start? Thanks .

 

It's your rear ABS sensor on the top of the rear differential. It's plastic and has a limited lifetime....

 

I agree, sensor mounted on rearend housing above the pan. They go out alot.

 

thanks guys

 

I had the same problem for a long time. I replaced the sensor twice and the problem would quickly (not quickly enough to get my money back) return.
Somewhere in these forums it was suggested to change the brake switch. The one on the pedal inside the truck. It's got like 6 contacts and one set was bad. It didn't effect the brake lights, it just thought the pedal was slightly depressed and after about 45 mph it threw the ABS code.
The first time I changed the pumkin sensor it was obviously bad because my speedo went out also.
Mail order the switch, it's like $8 with shipping, installation is easy but a little tricky. The plunger length adjust is a one time deal so follow directions.