GM guys are gonna scratch their heads on this one. If you read and reply then bless you and thanks even if it's no help. I'm an electrician 40 yrs..alone on this stinks. So, 09 silverado 5.3 ltz 4x4 went out 4 days ago to start it up...dead battery checked with volt meter. Humm?? 5 yr Battery only 18 mo old. Put it on a charge at 15amps 2.5 hrs battery back up full. I disconnected the Batt and put a standard 15 second crank load on it to access the condition nothing unusual so I did the load test 20 more times and it never pulled the batt down below 12.7. Recharged the batt afterwhich and it held a charge 13.4v overnite. Reconnected the battery pos then neg and upon touching the neg connection to the post, there was and audible and visible spark at the post not huge but, more than expected since the resting amp draw should have been 0.50-.100 ma. I continued with the connection and tightened both cables truck started up quickly and fine that's when all hell breaks loose...Dash lights galore...trailer brake service light, ABS, traction control, check engine...wow!~ what a light show...nothing smoking in or out no smells, gauges are normal.. nominal lights work horn blows heater ac radio windows all appears to be functioning fine so took it for a spin let it warm to normal operating temp to see if check engine light goes off and V8 to V4 engine indicator resumes proper function..CE.light went off, v8-v4 function normal and then back home put in park, the engine won't shut off key turned key out. All dash lights go out everything powers down when key off as expected but the engine stays running. I cut the intake air supply to kill it. Got back in started it back up just fine same condition with cluster and not shutting the engine off with several attempts. let it sit overnight next morning dead batt. Recharged batt to full 13.6 volts and holding and began to perform a amp draw test at the batt post. After disconnect of neg post and connecting amp meter, The amp meter connection caused the same small spark on touching the post and the horn started the panic honking???? What? I forgot to look at the reading on the meter to see the draw with the horn going so pulled the horn fuse and a retest. The draw was crazy high at a full 9.5 amps not like the expected draw say, if as light inside was on or something smaller so no wonder the spark??? Now what? Pulled power off the alternator for diode check no change same amp draw...starter cable off same amp draw...nothing I tried disconnecting in all fused circuits would stop the draw. Never befor all these years this truck a single problem electrical or otherwise. Will the dealership go crazy finding nothing charge me arm an leg? Some foul instance in the PCM or more so even the BCM? Funniest thing I've ever seen. No answers in any forum searched for days on end. Nothing in the books. Looking for some bright minds here to tell me I did something wrong or take it to the dealer anyway give it your best shot. Thanks Kevin.