Hi there I have a low mileage (85,000kms) 2011 rx350 premium (no gps).

recently twice in the last month the car has not been able to be started after driving briefly and trying to be restarted. Both times what happened was after a short drive to a store, when trying to lock the car from the fob, the car would not lock and seemed dead electrically. Getting back into the car, the car would not start (fob held right against start button) and the entire dashboard was unlit. After about 10minutes of waiting, suddenly another attempt worked, the dash lit up and the car started flawlessly. (No struggle). Both times after this, the time and trip computer were reset as if the battery had been disconnected. The car has been operating normally 95% of the time otherwise this month.

I checked the voltage of the battery and it is at 12.3v at about 0C outdoor temperature which seems fine. It is a 1.5year old OEM Lexus battery.

i checked the remote battery and its down to 2.88v which still should be in spec, but I replaced it anyways. Though I doubt this is the culprit as the car’s losing time and trip computer data in these events.

when the car did start up each time, three lights came up in the dash for a few seconds and went away. Check engine, power steering and battery I believe. See attachment

 

12.3 volts is much too low. You likely have a dying battery.

 

it was 0c (32f) outside when I measured the voltage (car sits outside) but yes it still probably should be 12.6

However the car starts flawless with no effort when this issue doesn’t occur.

so not sure what is causing this? And for the car to go so dead that it loses trip computer and time

 

You need a new battery. Get an AGM battery.

 

why would I need a new battery after 1.5 years on a new Lexus oem battery? Isn’t that curing the symptom and not the disease? The car regularly gets driven on the highway and should be charged up well. Never had a dead battery due to leaving lights on or anything.

could This be a symptom of a failing charging system?

 

Yes it could be an alternator issue. But keep in mind that any battery can die at any time, including brand-new ones. Some "new" batteries sit on the shelf for 6 to 12 months before someone purchases them. I always check the build date sticker on the battery casing (month/year) and grab the freshest one available.

 

Frustrating thing is that the issue is intermittent.

Logically you will rule out the battery and the charging system [yes both]. They are also so interdependent that you need a hard and consistent fail to diagnose. Swapping can hep.

This is the area one goes by hunches and tries to eliminate/isolate. Looking back in history as to what event brought the onset of the problem can be very helpful.

My #1 would be loose terminal. Visual inspection will not help. One needs to physically twist the terminal and shake the thick wires.
My #2 would be aftermarket accessory.

I can be way off in my 2 calls as I myself have had a bad fuel pump which I honestly stumbled into discovering ... I just tapped on the pump and luckily it was quite environment and I could hear the pump come to life.

Regrettably I try to diagnose logically and intermittent problem can be explained logically only after being diagnosed/repaired. Time for AI in diagnosing vehicle problems.

Salim

 

thanks Salim, I will check the terminals. How about chassis ground?

only aftermarket item is the trailer hitch wiring into oem wiring harness … maybe a short there? But you’d think that would blow a fuse at worst…

 

I don't think it is a problem due to short and this is my reasoning ..
If there is an intermittent leakage issue then the battery will deplete and will not recover till is charged. If there is a short, a fuse will pop. Only thing that negates this is a weak battery which will require charge up [by alternator or external charger].

Missing/loose ground:
Possible but some work was done and some one forgot to secure the ground. You will need history. The grounding is done in multiple places and for the starter [which draws lots of current] the thick wires from the battery need to be traced and wiggled. One test is to connect a voltmeter on - of the battery and the other end on the engine block and engage the starter. If you happen to do it when the starter does not work [intermittent fail] you will see a voltage. Normally with ground strap it should be at the same potential [0v]

Again, my logical thinking is of little use in debugging. Luck plays a major role.

Salim

 

so some further testing:

1) the terminal clamps are tight and clean

2) tested voltage with the car running and got 13.95v

3) tested voltage after shut down, and with the HID lights delay running after the car is off, the voltage drops into the 11s and then once they kick off, it bounces back up to 12.1v and slowly creeps its way back up to 12.3v.

perhaps it is a weak battery that is getting killed by the DRL or HIDs staying on after the car is stopped. I checked the manufacture date and it is 10/22 sticker on the battery, bought OEM from the dealer.

 

It seems I misunderstood and was thrown off-course by "intermittent". To me intermittent would be if the vehicle starts without charging up the battery. The above seems to indicate a discharge condition and it needs a boost or an external charge to bring the battery voltage up enough to start.

By my new understanding the causes are
a) weak battery
b) more than expected draw
c) not enough run time which does not allow charging during running to recover any expected draw during use.

Salim
PS: I have my lights go out as soon as I open the driver's door. [I have lighted garage so it works for me]

 

Hi Salim,

It is truly intermittent as it only happened 2x in the last 2 months now (and not in the last 2 weeks of daily use).

The battery has never been externally charged. Only by the alternator.

maybe i should turn off the exit light delay on the headlights?

 

Did you ever found the solution? I am having very similar issue and I cant figure whats wrong
QUOTE=kmax1980;11672399]Hi Salim,

It is truly intermittent as it only happened 2x in the last 2 months now (and not in the last 2 weeks of daily use).

The battery has never been externally charged. Only by the alternator.

maybe i should turn off the exit light delay on the headlights?[/QUOTE]

 

Getting the battery tested is one of the easiest thing to do and the auto parts shops do it for free [in the hope of selling you new battery].

If you are willing to throw some money at the vehicle ... if your battery is 5 yrs old ... just go ahead and replace it.

Sorry to repeat ... is it a starting [getting the starter to spin not necessarily engine running] problem or you get dead dash.

Salim

 

At random times RX is completely dead, it wont unlock and i open the door with manual key and inside everything is dead but after a minute it comes back alive and on first attempt it start but dies immediately but on second attempt everything is back to normal. Battery reads around 12.5v and its 8 months old Costco agm battery