How Long To Drain Power From Car Once Battery Disconnected?

[Aaron G]

I did a search for an answer and came back without  one. I bought a new Toyota Battery for my IS220D and got a mobile mechanic to replace it because I thought you had to get a tool to reset the ECU to the new Battery - or it would think it was the old one and make the alternator work it harder, and wreck it.

Apparently the IS220 doesn't have this feature. ?. I watched the mechanic look for it and he told me it wasn't there...
Anyway, he didn't know you had to reset the windows. So instead of reading the manual like I should have (because I'm a plonker) I looked it up on Youtube and bodged it.

Now they've stopped flashing and only the driver window works. So I disconnect the Battery (negative first, negative last) and left it off for a day. But on reconnecting it, the windows don't go into their flashing mode and everything is still stored on the car - like satnav locations, etc.

So I'm assuming there was still power in the car and it didn't drain?. Now I don't really want to mess with that idea of connecting the positive lead to the negative one to drain the power out of the car and 'reset' it because electrical stuff on modern cars makes me nervous.

So I was wondering if I just left it long enough, would the residual power drain out of the car?.

Thanks.

-Hope I haven't wrecked all the windows on the car. I just powered the driver one all the way down for a second and all the way up for another one. 🤪

[Texas]

Battery disconnected for approx 20mins is enough to dissipate any residual current, this is the time recommended before working on the SRS components so will apply to other not so critical components.

 

[johnatg]

Just drive each window up and down with its own switch on its own door. That will reset them and then they'll all work from the drivers door. Pause for a few seconds at the up/down positions

You don't need to do all this draining stuff unless you're working on the airbags or seat belts. 

[Texas]

Like this

 

[Aaron G]

Before I reveal how much of a plonker I am, I'll just mention that I'm about 20 years behind the cars that came out 15 years ago in terms of technology. My first car as a teen was a Ford Escort, and my only other car was a 2003 Vauxhall Astra. So putting me in a 2006 Lexus is like putting Fred Flinstone in a dodgem.

So after leaving the car disconnected for a day, reconnecting, getting back in and sitting there for a few minutes waiting for lightning to strike because the window lights still weren't flashing...I realised had the child locks on.
Turning them off caused the lights to start flashing again, and then I did what it says to do in the manual.

If I ever want to get rid of the mother-in-law one heat wave summer though, I'll have to remember this one.

[Texas]

A result is a result so bonus.👍

[Aaron G]

I can't say for sure if the power was drained from the car though. On the one hand I had just cleaned the MAF sensor and on the other, the satnav points were all still in the memory.

So if the ecu had been restarted because it was drained, maybe it defaulted to just under 1000 rpm while idle. Becuase if the ECU settings were still in there, it would have been idling higher when I reinstalled it.

I dunno.