My 2006 Avalanche is having an issue. two weeks ago went to start the truck and it had no power at all. Battery seamed completely dead. Went and bought a new battery and it started right up. Today (two weeks later) went to start and again nothing happened. No lights, sounds absolutely no response. Battery read at 12 volts and said was fully charged with my battery charger. I disconnected the battery to check the cables found no issues with them. Reinstalled the battery cables and saw the lights in the truck turn on since the door was open. tried starting the truck and it started right up as usual. alternator was charging with no issues and the starter worked fine as well. Obviously something was preventing power from the battery getting to where it needs to go. Any ideas what I need to look at?

 

poor wire connection prob. check your positive cable and the neg

 

 

 

"when I disconnect the ground on the battery and measure the positive cable to the battery ground terminal I get 12 volts. If I then try the ground on the motor I get a millicts reading. I’m loosing my 12 volts. Does this mean I have a bad ground wire?"
If you mean milli volts yes. Take your ohm meter read frame ground to battery cable, should be 0 or so, if not, replace the ground cable. Should say to read the frame end to the battery end of the ground cable.