After doing my differental what are mechanics of how the ABS works. Please no "it works just fine for me."

 

This may or may not be right, but it's my best understanding of the system...

The ABS sensor reads off the ABS tone ring. If the sensor stops seeing movement in the tone ring, it activates a solenoid that pulses the brake fluid so there isn't constant pressure on the brakes so they can't lock up and stay locked.

If you've ever stopped hard enough to activate ABS, you'll feel it go: skirk......skirk.......skirk......etc. where it is pulsing the brakes, instead of a constant screeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeech.

^ I know, very scientific explanation right :P

 

You can go to www.howstuffworks.com for good pictures and probably a video on it.

 

I have had it actuate one and it was when I had one wheel on ice and the other on pavement going down hill and I had the ABS light on and the brake pedal pulsing like it should. I am trying to figure out when sensed one wheel still turning and the other is locked up in a skid.

 

First off, we are talking about the rear ABS right? If so, that is a very interesting question!!!

I've had one wheel lock up (b/c the drums weren't evenly adjusted) and the ABS didn't activate. I know it didn't activate it because the other wheel was still spinning, therefore the differential had to be spinning and therefore the tone ring had to still be spinning for the sensor to read. I can't think of a single reason why only one wheel locking up would stop the differential from moving!

What year is your truck?

 

Yes rear ABS.