Silverado wont start - completely dead - jump doesnt help

[Jennifer 7097]

HI. For the last few months my truck wouldnt start sometimes but after a few turns, it would start. Now, it is completely dead. I have tried getting a jump, wouldnt start and have it hooked up to a battery charger and it says battery is charged, still dead. I have checked the connections and the wires. I am at a loss. I have had 2 mechanics out to look at it and both gave completely different answers and wanted a ton of money. Thought I would try here. Thank you in advance. 

[Jsdirt]

There's literally 100 things that could cause this. First thing I'd do is the easiest - check all the fuses in the cab and under the hood. If those all check out, the next thing I'd do is play swaptronics with the start relay in the underhood fuse box with another relay, like the A/C clutch relay - if it suddenly cranks, then you just need to replace the relay (or go without A/C). 

 

If all that checks out, you'll need to have a helper hold the key in the crank position while checking for power at the start wire (small wire) on the starter. If you have no power there, you'll need to figure out why. If that's something you're up for tackling, get a wiring diagram off AllData DIY (about $15 or so), and test the wiring all the way up to the key switch until you find the issue. That's the easy stuff off the top of my head.

 

Other issues that can affect cranking are the BCM (Body Control Module), CAN lines (communication), security faults, and the list goes on.

[Doug_Scott]

Also try putting shifter into neutral and see it if will crank as well.  The most common thing is bad battery cable connection.  Do not just look at the connection and think it looks clean, take both cables off the battery, negative cable first, clean terminals and posts.  Look carefully where wire enters terminal for any swelling or white powder.  Do the same for the other end of both cables, making sure there is no bulging or white powder at end of wire.  When re-connecting cables, connect negative last on battery.