Greg Robbins

I have a 2011 GMC Canyon 4x4 3.7 liter automatic that occasionally, very random, overnight, the battery will drain down to nothing so that the dash does not even light up when key is turned on. Nothing. Not a glimmer of light. As soon as the booster pack is connected to the battery, the truck will start and then be good, sometimes, for a few days. Sometimes it won't start all day long without the booster pack. We have changed out some of the power relays. Checked for bad connections to ground and to the system. We have connected an AMP meter to the battery positive post ,in series with the battery and checked for current drain when shutting off the ignition. It draws approx. 2.5 amps for a few seconds then drops to .100 milli amps for a few seconds, then down to 0.001 amps and stays there until key is turned on again where it goes back up to approx. 2.5 to 3.0 amps and again repeats the drops when shut off. We have even install a 0.5 amp battery maintainer that gets plugged in at night. Even then some mornings the dash is dead on key on and no start. Any Ideas?????