A funny thing happened on the way to the office

[Gliderpilot]

This one is peculiar. The car had been stood for a few days and when I came to start it everything happened as it should except the ready light would not came on. Tried it a couple of times but still no good. The 12v Battery pulled in the HV Battery isolators as the various noises got faster i.e. the brake pressure pump got faster etc. So I tried a different key and it started, so I did my short run to the grandsons new flat and then used the original key to drive home with no problems.
1. does the key fob Battery power the key ID.
2. can the car "forget" the key, and then remember it again.

Cheers.

[DanD]

1. yes, I believe that this is the case

2. yes, when the Battery within the key is due for a replacement. The signal from the battery/key may be too weak

 

 

[LukasG]

Both yes.

 

[Gliderpilot]

Changed the Battery in the fob, no problems since.

[GSLV6]

Lexus recommend changing key fob batteries every few years to avoid this problem, which is good advice.