Anyone know the why, how and when sleep mode functions? Apparently, this was the reason why my battery went dead causing 26 other control faults. Any thoughts are of course appreciated. Thanks.

Only sleep mode I'm aware of is after 16 mins the car resets.

This means things like heated seat setting are remember uptil this time if you stop for fuel etc.

Still after 30 min or more I can here my car being active!

Active cruise control transmitter emitting high frequency sound in intervals. Often happens when I wash the car. Is this dangerous maybe? Radar is no god for your healt if you are to close to the transmitter!

Some other sounds now and then. Sounds like fuel pump or some valve closing under the car?

Gremlins or what? Very strange! :huh:

you know on the shift lever if you have an automatic, the light when the lever is in Park remains on considerably for quite awhile. before the software upgrade it would disappear in about 15 min. now its longer. agree with the sounds, motor winding down, etc., i really don't care as long asthe battery doesn't get drained again.

Different car manufacturers have different "sleep" modes, but basically there is an ECU or a network of ECUs that are connected to battery. After ignition is off for a certain amount of time, the ECUs go to sleep meaning that they are not running full up, but if they receive a wakeup signal (Door/Trunk opening, remote unlock signal, etc.) They wake up and get ready for operation.

Here lately, the automotive industry has been doing periodic wakups which means that they wake up without a signal. This allows them to calibrate certain ECU functions while they know the car is off and everything is "stable". Most of the time, if your battery is draining, then one of the ECUs on the car has a bad part that increases the sleep current to an unacceptable value or the periodic timing on one of the ECUs is malfunctioning and it is waking up more that it is supposed to. Either problem can potentially drain your battery.