This is from memory so bear with me.

To replace the crank sensor you need to disconnect the neg. batt. cable, remove the pass. side tire, the splash gaurd around the crank balancer, the sepentine belt, then remove the harmonic balancer. The sensor is to the right side of the balancer and is held on w/ 2 bolts. There should be a plastic shield around it as well. Disconnect the electrical harness from it, remove the 2 bolts and there you go.

In order to remove the crank bolt, remove the inspection cover from the trans so you can see the bottom of the flywheel and clamp a vice grip on the flywheel. Then when you spin the motor backwards it will catch on the vicegrip and the bolt will come out. Be warned- that bolt probably has orange loctite on it from the factory and is torqued to 110 ft/lb. so it may fight you. Best bet would be a good impact wrench, or a long cheater bar. You will also need some small 4" long bolts in the correct pitch/thread to remove the balancer as most on the market do not come with the proper ones. I got mine at True Value.

When you go to reinstall the balancer be 100% sure that the KEY ON THE CRANKSHAFT IS LINED UP WITH THE SLOT IN THE BALANCER!!! If you don't you will screw up the woodruff key and possibly the crank slot. I reused my stock crank bolt even though technically it is a torque to yield bolt and should be replaced. Your call there. Dealer has it if you want a new one. Make sure it is properly torqued after install. Then remove the vicegrips from the flywheel and reinstall the cover. The rest should be pretty straight forward.

And to find out what hub is having the issue and needs to be replaced, have it scanned on either a GM Tech II scanner, or something that can read ABS codes as most generic parts store scanners will not read these. Dealer may want $50-$100 for a scan. Once you find out which one it is try disconnecting the harness behind that wheel and cleaning it out as they can get corroded and cause an ABS light. If this doesn't work then get a TIMKIN hub from Rock Auto and call it good.