2007 Chevy Silverado, 5.3 v8, Automatic, single cab, long bed and manual windows, 69K miles, until 2 years ago my main transportation was motorcycles but I moved to Seneca Falls and I turned 70, low milage on the truck. PROBLEM: The battery drains after sitting for a few days and the console voltage gauge is pegged past 19v. I changed the battery(6 yrs old) in June (Walmart) for this issue. I went back to Walmart yesterday and they replaced the battery again after the June battery failed the deep load test. I cleared the ECM using the 1 ohm, 10-watt drain method and my console volt gauge once again showed the same (14.7v) as a meter on the alternator...but I noticed after each engine stop the console gauge reads more until it was passed 19v. Clearing the ECM every day is tedious so I have a pegged volt meter gauge. The alternator still shows a steady 14.7v. Last night the new battery showed 13.05 this morning it was 12.5v. The shop looked at it for 3 hrs and could not find a problem. No charge. My next step is to buy a wiring diagram (any online sources?) and look at relays?? I think you are in the god zone for car repairs so any advice would be great. Thank you
I can't find where to get the resister?!!!
Well, Amazon had them but you don't need one. As @imperator noted:
resistors are a waste of time. You can just hold the brake for 10 seconds instead.
You don't need a resistor. Just disconnect the battery, then hold your brake lights on or turn your head lights on or your dome/navigation lights, etc. These actions will drain the residual current from the system quickly, faster than using the 'resistor method' and it cost nothing.
Inspect and clean the battery terminals and grounds, have battery and alternator load tested. If all good and still a draw. Check specifically for a parasitic draw. That shop could have done this in three hours
I can't find where to get the resister?!!!
I cleared the ECM using the 1 ohm, 10-watt drain method
resistors are a waste of time. You can just hold the brake for 10 seconds instead.
The battery was defective and replaced. I think the battery drain is fixed. Give it a couple of days. My next issue is the voltage gauge fix. I can reset the gauge to the correct reading but after every engine start the gauge shows higher voltage even though it is still reading 14.7 at the alternator with a meter. The reset is to clear the ECM with the 1 ohm 10-watt resistor. Next, I am going to look at relays or something that is not releasing the voltage reading when the engine is shut down. Thanks for the reading material, hopefully, I can get smart or just lucky. Thank you. It is only 37 outside today so I got a longer work window.
OK, wouldn't bother resetting ECU as it's just the voltage gauge reading being off which is apparently a known issue in that vehicle(I would still check the battery chassis ground) ; https://www.trifive.com/threads/07-silverado-pegged-voltmeter.203708/
No answer yet. The battery drain was gone for a while and now it is back. I went and bought a battery maintainer yesterday and I am back looking for answers.
Status. Start again from step one. Charge the battery and start looking for drains in the fuses and relays. When I thought it was fixed the overall drain was .35 amps and today I am not sure. I am a shade tree guy(no garage or barn, just a tarp) and it is raining in NY and I am going to the grandson's birthday party. Maybe tomorrow.
The gauge is still pegged, another problem. Thanks to my Harley's I still have less than 70k miles. Thanks to BamaNomad's post. https://www.trifive.com/threads/07-silverado-pegged-voltmeter.203708/This is what it looks like 
The battery drain was gone for a while and now it is back.
Voltage gauge repair kit info on ebay. I will do an update after I repair it. ~$30.00 https://www.ebay.com/itm/126223224814?fits=Year%3A2007%7CModel%3ASilverado+1500%7CMake%3AChevrolet&itmmeta=01HVBSPB9X1KVTFXMRCSA0CJH0&hash=item1d637d8fee:g:ih4AAOSwGIBlW0Wn&itmprp=enc%3AAQAJAAABEAGkMXqvWkUa2Li6KKJwG8P60S1TEXbUH9E80qDf1b%2BLYOpLdxtO5cSxW8LZnQDi45zANPmfAxEBSIZmyb7bQoP1SGZFOy5RHVCJ9bFNhNqfwcL2Z7sm868lfCRIo1hrnRrUl%2FAzFwfH3XaHuRfvCzG7YX5qmF6KrvhKkgkjT7Bo%2BEODdk8dwo9s5MG%2BP3dEMnsYz6AYHFzFjLjTFzicsBRjwiKztxFaxJc20%2FxYUXZfsVFEn7LFpJObGidYB0o4GVu07ecmc3y7ieAlNt7csGQfPHpkOPJo%2B2WbMQQ4GmsOmbr8LmOyuWnLKCN7x%2BCzC3vOUtcWPVzzYqgxwmihZqfQyCpZn083hWAYd4LZpiN5%7Ctkp%3ABFBMirXZ-dpj
for $30 you're going to get an extremely junky soldering iron with no temperature control that will easily ruin your cluster. Proceed with great caution.