I have a 2000 Blazer 2WD 4.3. The ABS light will come on while driving and with in a few block or a few miles go out again. Sometimes it will come on while stopped at a light and then go out again right after I start moving again. I scanned the code and I get a C0220 which I Google and the only thing I find is "Left front ABS channel in release too long." Anybody have an idea of what that would mean? The brakes feel fine and I have no problem stopping.

 

Have you looked up that code in here? Kyle (SWARTLKK) has posts for all the DTC's.
Personally when I got my ABS light or a DTC related to ABS it was a dirty ABS sensor. There's a link in here on how to clean the sensor.
Ok I just tried to google C0220 & came up with nothing related to a blazer, have you got that code right?

 

I scanned the code again and this time it came up C0221 which is simply an open circuit on right front. So I must have a intermittent connection some where on the right sensor. I scanned it three times and each time it comes up C0221. I swear it was C0220 the first time.

 

It likely is a broken wire between the RF WSS & it's connector. If the wire isn't routed properly, it can get pinched during steering and/or suspension articulation. Even if it is routed properly, road debris/etc can stag the wire & damage it without noticeably marring the jacket.

Testing the sensor using the method described in the tech article on slow speed ABS activation (first section of the index linked to in my signature) while flexing the wiring should show the fault. You can try to splice in new wires between the sensor & the connector or you can just replace the sensor.

 

Over the weekend I pulled the connector apart and shot some contact cleaner into it and pushed the connector back together a few times to give the contacts some wiping action. I then reset the code and so far the light hasn't come on.

 

Hopefully that cures the problem for you. If it is a wiring problem, the movement of the cable may have been enough to complete the circuit again and it will likely come back.

Did the connection look dirty?

 

Actually the connection didn't look dirty and the problem has come back but it doesn't seem to be as frequent. I've ordered a factory service manual so I can find both ends of the wire and test it properly.