Rx450H 2012 No Ready Light

[Barry7]

I am a new owner of a 2012 RX450H and picked the car up 1 week ago. Since then, on 4 occasions the ready light has failed to come on so unable to start my journey.

The first time, I thought I was doing something wrong and then after several minutes suddenly all was well. However, whilst panicking over the situation I did wonder if the aux Battery had gone flat but when it started dismissed this as pilot error.

But since then it has done the same 3 more times. Second time, very cold frosty morning go to start - no ready light! Get out the car, lock and unlock it, get in - all OK. Third time my wife was driving, she had used it earlier to go shopping locally with no problems, but some hours later the same situation to the point where she had to use our other car to collect me from work.

When we returned home, I tried and still the ready light would not come on. Tried both key fobs individually, and even touched the Lexus sign to the start button but still no ready light. I then noticed the LED reading light had been left on and after this was turned off and disabled the automatic headlights the ready light came on after about thirty seconds of pressing the start button, and away we went to give the car a good run.

Could this be as simple as the aux Battery being low on charge, stopping the ready light showing, and then getting some sort of cross charge from the drive Battery, just enough to enable it to work?

Or is it a more serious issue?

I'm planning to put my multi-meter in the car and check the standing voltage on the aux Battery if the problem re-occur, but any advise would be most welcome.

Love the car to drive but this is making me feel anxious every time I go out to start it.

[RXJasonRX]

hello i doubt that would happen 3 times in a row. I would take it back to where you bought it and get another 1.

[rayaans]

Car's still under warranty if its 2012 model isnt it? Take it to the dealers ASAP

[Barry7]

Ok, done the checks and found the Aux Battery when disconected at 10.6volts, re-conected and checked again and found the voltage had risen to 12.4volts, this must be a back feed via the inverter to the Aux Battery.

Tested the Aux Battery and it failed the test so new Battery required.

I spoke to my dealer (Sunday) and they agree and are getting me a new one for Monday afternoon.

The guy at the dealer said that the Aux Battery is only for power to the Aux circuits, hence no Ready Light and then no start.

Connected Jump pack to Aux Battery and all back to normal, and charge rate at 14.2 volts when running.

I will get the dealer to check the whole system for faults tomorrow, but lets hope this is the answer............

[nelmo]

That was the same symptoms I had and replacing the 12V Battery fixed it all.

[Barry7]

My lovely Lexus is all better now! Went to dealer this morning who tested the old aux Battery and confirmed it was unserviceable, so replaced it under warranty.

All is well now, but one thing I have noticed is that the fuel consumption has improved and the petrol engine seems to be running a lot less when stationary, I can only assume that the system was sensing the low charge in the aux Battery and was attempting to recharge it far more than normal.

**Please note: if you are attempting to check the aux Battery yourself, you must remember to disconnect it from the car first otherwise you will get a false reading across the terminals due to back-feed from the drive Battery system. (Mine was showing 10.6 volts disconnected and 12.2 connected).**

[F.A.]

Glad it is all sorted but worrying that your Battery died just after 3 years

[Barry7]

Yes it is a bit of a worry, especially as I got nine years out of the Battery on my very old Camry........!

[F.A.]

This is what worries me. My wife only drives 14 miles to work and back so worried this will be a problem for the aux Battery. It should get a good run on the weekend though

[Barry7]

Fourteen miles will be fine to recharge a good aux Battery, if you are at all worried have the Battery tested, and remember the aux Battery only has to wake up the drive Battery system, then it has done its job, hence it is so small.