Battery drained

[peasoup39]

Just bought the car a few weeks ago had the cambelt done and started to enjoy. a Lexus again.

Tried to start it on Friday after a few days idle and Battery was completely dead. So dead nothing would show not even dashboard lights. It was if the Battery had been disconnected.

Changed the Battery from another one of my cars and the car fired up. Left it for a day, went to start it and it was flat. Not totally but starter solenoid would just repeatedly click.

Checked voltage and  it was down to 8 volts so suspect the spare Battery is gone, however took off the earth lead and checked with multimeter which showed a current drain of 1 amp.

With all electrical items off  and presumably the alarm/ immobiliser not being armed this appears to be a big drain on the Battery when idle.

Is  a constant 1 amp drain normal or is there a common problem with these cars that rears it head from time to time?

I will be off to get both batteries tested in the morning as a first step.but would welcome any other suggestions

[ColinBarber]

That isn't normal. Once all the systems have completed powered down (some say it can take up to 30 mins after ignition turned off, but at least 10 mins) you shouldn't get more than 50mA drain.

I'd start to pull interior fuses one by one to see which circuit is consuming all that power.

The audio amp has been known to go faulty in the SC430 which causes excessive Battery drain so start there.

[Texas]

Interior boot light going out when boot closed is it?

[Herbie]

1 hour ago, ColinBarber said:

I'd start to pull interior fuses one by one to see which circuit is consuming all that power.

While Colin generally gives good advice, with due respect to him I wouldn't do that as it could reset the very thing that's causing the problem and then you wouldn't have a problem to find.

There are plenty Youtube videos on finding parasitic drains and this is just one of them:

 

 

[peasoup39]

Thanks for the quick responses

With regards to the boot light i am not sure where the switch is so took out the lights but still had the same drain. they are also LED bulbs so drain from them would be minuscule.

First thing tomorrow its Battery tests.

The video is a brilliant way of testing in a quick and simple way so that's my next move.

Will keep you posted

[Neil E]

For that much current drain I would suspect the audio amp. Is it operating normally and if you turn the head unit off before the ignition, does that stop the drain?