Auto Electronics: 2001 chevy impala ls battery drain and no crank some times, parasitic drain test, battery drain

Question
If my car sits for 3 or 2 days the battery dies. Also once every couple of months
the car will not crank over. In regards to the no crank. the battery is charged at
that point. i will see dash lights but when i go to start the car nothing happens.
if i wait ten minutes the car will start. i don't know if this 2 separate problems or
if they are tied together.

Answer
It’s hard to say whether you have one problem or two. I would start with the apparent battery drain problem first, the intermittent no start is inherently more difficult to diagnose and may be fixed with the first repair. The first thing that needs to be done in any no start condition, is to have the battery load tested to make sure it is capable of taking and maintaining a charge. Once the battery is deemed good with clean tight connections to the system, a parasitic drain test should be performed. I don’t know what kinds of tools you have or even if you are planning on doing the repair yourself, but the old method of checking for a drain with a test light will not work on this vehicle. Diagnosis of this problem can get very involved, the cause of an excessive drain can range from a bad diode in the alternator to a glove box light that stays on, or even a bad module that won’t go into ‘sleep mode’. All vehicles have some residual parasitic drain even after all the systems modules have gone into ‘sleep mode’. The ballpark figure for this is less than 50 milliamperes. Rather than give you details on how to proceed with testing I will tell you to try and figure out what might have caused the drain problem, with the hope that it will lead to the fix. Try to think about what changes have been made to the vehicle that might have caused this to begin with. Have there been any repairs performed on the vehicle lately, including body repairs? Are there any aftermarket devices installed, new sound system, remote starter or anti-theft system? These are always primary suspects when chasing down a battery drain problem. Checking under the hood, make sure the wiring harness isn’t worn through in the area where it passes near the AC accumulator. Finally, this vehicle is known to have problems with the ignition switch and/or ignition lock cylinder (might be the cause of your second problem).
Hope this helps, Don