I have an 02 3500.. the ABS and BRAKE light come on and off intermitently ANY ideas why ??

 

Whats you weather conditions like
wet, lots o snow
been driving a lot on really slippery stuff with los of wheel spin?
for example when plowing my ABS will get confused and give me a light
could be a sensor starting to go south, a bad/corroded connection,
pinched/rubbed sensor wire
do you have the 4 wheel ABS or the rear wheel Antilock system? I/m not sure what all was out there on the 02s

 

Your ABS sensor is bad. Do a search on this site on how to check the continuity and resistance of the lines (either 2 or 4WABS).... On a side note, if you need to change your wheel bearings up front the Timken bearings come with new sensors and lines.... RockAuto.com has the stuff....

 

Check the wiring to the rear sensor for bare spots from rubbing.
My ABS sensor harness did it right where it passed beside the parking brake cable near the driver's side rear wheel.
It was worn all the way to the bare copper and was shorting out on the parking cable.
Drove me nutz for two days until I found it.

 

When I pulled out my rear sensor it basically fell apart in my hands. Luckily I got all the pieces out of the diff opening. This should be a thing that is changed every 5-8 years, I believe, so the plastic doesn't fall apart....

 

My ABS light was flashing intermittently. Turns out my bearing was bad (luckily hadn't siezed on me yet) causing the sensor to rub against the wheel/hub, causing the light to flash. New bearing (SKF from Napa) with sensor included, and the CAB reset itself and no more light. Let me add, it was the left front wheel bearing which was bad. Originally thought it was the VSS in the rear diff as at first the light only came on above 60mph, so had one on hand for $40 from Checker, but ended up taking it back.

 

Mine was doing the same thing of turning on and off a different times. It turns out that it was due to my rear speed sensor.