I have a 2005 Avalanche Z71. I just replaced the battery after hooking it up the lights on the truck and on the dash started to flash. Had the alternator checked at autozone it showed it was fine. When you turn on the head Light switch they stop flashing,but restart when you turn it off. also the power steering is a little sluggish when turning the weel from a stop. From what I've read this indicates a bad alternator. I've checked what grounds I could find underneath the truck. I've also tryed unhooking the head light dash switch think maybe that was the problem. Nope not it. Thats about all the info i can think of. Need a little help on figuring out this problem. Oh, and the truck runs fine.

 

grab yourself a cheap multimeter and measure the voltage