Vehicle: 2002 Highlander, 6 cylinder. Note: have a new battery, even had the new battery swapped for another. I am having a problem that on the surface appears to be a battery issue, but the overall problem, the initial process to get the vehicle started, and the following results just do not add up in regards to the problem being the battery. Vehicle can sit for two weeks and will start right up. But on occasion can drive the vehicle, stop, turn off engine and return in a hour or so and car has all the systems of a dead battery – no headlights, no dome light, no radio, etc. Jump vehicle and starts right up. Drive a few miles, turn off engine and no more “dead battery” problem. Take vehicle to the shop where bought the battery and they do a full battery / system check and no problems. Under full load battery checks OK, battery (engine off) checks at 12.95 volts, (engine running) checks at 14.25 volts, and with nothing on / key in off position system is pulling 1.2 amps (which I understand is normal re: clock, etc.). If battery is bad how can it charge up so fast via the alternator only – no external charging source applied. This has happened 3 times in past 4 months. Is there a component that could get hot, temporarily short out giving the vehicle the “appearance” of having a dead battery, but then be “shocked” back to life when vehicle is jumped? Any ideas or random thoughts will be appreciated. Thanks Bob

Sounds like a bad battery connection to me. Mine does the same thing. The battery terminals look clean, but the connection is not the best.
When it does it again, with a wrench, smack or adjust the battery terminals and see if it starts right up.

Will do. Thanks Bob

Did as suggested. All looked good. But did clean with with electronic terminal cleaner and ensured all were tight. Have not had problem since original post - but then again it does not happen all that often. Any other suggestions? Thanks Bob

The sounds are all very common of just a loose Terminal as the person before me suggested. Loose connections can be a real headache and huge frustration when you find out you didn't need that jump after all.

What the loose connection was doing was a small short of the system, which is why the jump starts and such would always work too. The clamps from the cables would give it that slight "snug" they needed. If you tightened them and cleaned I'm pretty sure you won't have any more issues.

Though i would suggest to check the cables themselves and make sure they're not the ones becoming loose from the terminal itself. Or if you have after market equipment like an Amplifier on the same terminal make sure those connections are good as well.
Check the connections on the starter as well, more or less ~ just follow the "main" leads and see if they're nice and snug. :)

Thanks, will continue tracing the cables / wires. Bob