2 Dead Batteries In 1 Week.....HELP!

Hey gang.  I have an 02 Avy Z71 and I just put in a replacement aftermarket stereo (Sony XAV-AX100) so I could have Carplay in the truck.  2 weeks after the install, my battery was completely dead.  I thought, "hey this battery is 9 years old so it was probably time to replace."  Went to NAPA and got a new battery and installed it on Tuesday.  Today (Sunday) went out to my truck and battery completely dead again!!!

Hooked up the car charger and noticed that the charge indicator would go from indicating "completely dead" to fully charged and then back again.  The interior lights would come on for a second and then turn off, in sync with the charger indicator needle.

Could I have somehow wired something wrong in the stereo?  It already had an aftermarket stereo so I just wired the harness like the existing radio was.  I'm not a techie type of person and don't have lots of gadgets to test circuits or anything.  Just trying to figure this this out.  I suppose I could trickle charge it back to full and get it to Best Buy or Car Toys and let them check the stereo wiring (which I suspect since this all has been happening since the new radio went in). 

But any other suggestions of things to check easily would be appreciated.

Chances are you hooked the ignition and battery leads up backwards. Get a volt meter and check your lines to verify they are correct.

In the '02 all the wiring you need is at the radio.

Battery lead should have constant battery power
Ignition lead should only have power when the ignition is on. If your '02 provides a RAP signal to the radio then if you shut off your ignition you will have power until you open the door or 10 minutes passes.

VERY easy to check. Place the negative probe on your radios negative and the positive on your ignition wire and then try the positive wire.
You will read about 12 volts when connected to a power lead.

Also how did you connect your wires?
Did you just twist them, use wire nuts, crimps or solder?
Note that twisting or wire nuts are a big no no in a vehicle.  Only crimping or soldering are viable solutions.

If this all sounds greek to you then take your truck to a professional and let them trouble shoot it before you damage your truck or your radio.

Rodney

Thanks Rodney.  All connections were crimped together.  I strongly suspect a wire or two were done incorrectly by the inept installer (me).  I have the battery on the trickle charger and someone who knows way more about this stuff has agreed to check it tomorrow afternoon.  So hopefully this is the issue and we'll be fixed shortly.  But thanks for the advice!  Guess I need to invest in a voltmeter.

JB