ericsan13

An hour ago I got to my car at my workplace garage and the battery was completely drained. A passing coworker informed me that the fog lights were on and he contacted reception (who never contacted me).

How is this possible?? The fog lights were off and even if they were on the car is idiot-proofed right?

This is a 2010 RX350 AWD w/Nav

LeoDLion

If you left the fog lights on, it will not turn off by itself. Therefore your battery will be drained if left for hours.

07LexusGuy

how are you able to leave just your fog lights on? The fog lights require the regular low beams to be on for them to be turned on as well.

I'm curious, did you do some custom wiring to your car? Could there be a short circuit somewhere?

ericsan13

Exactly what I thought about the low beams. There is no custom wiring on my car.

I checked later and I can't think of anyway to keep the fog lights turned on after i left my car. I checked the fuses and everything looked fine.

Since the power is electronically controlled, how is it possible for a short circuit to happen?

vlad_a

Your conclusions are based on what the coworker said. The headlights may have been on also.
The question is, what position was the headlight stalk in when you got to the car?

kitlz

There is also a setting for how long the headlights stay on when in the auto position. I think it's 90 seconds, 60 seconds, 30 seconds and off. I don't know what happens when off is selected. Might want to check that too since the fog lights come on with the headlights.

vlad_a

I have mine set to OFF. As soon as you open the door, the lights turn off. I find it most convenient as you know the lights are off right away. However, these settings only work in Auto. If the lights are set to Parking or ON, they do not turn off on their own (need to do more experimenting).

kitlz

Thanks vlad_a. I usually manually turn them off before I get out of the RX. Maybe I'll turn the setting to off and save myself the effort.

ericsan13

The fog lights were off and the headlamps were set to auto. I usually press the lock button when walking away from my car to turn the headlights off. Coworker specifically told me that only the fog lights were off.

Is it possible the alarm was triggered and caused the fog lights to remain on as an indicator? When I was jumping my car, the first thing it did was start honking and flashing...

vlad_a

I would suspect the fog relay. Maybe it got stuck. It is hard to trigger the stock alarm without causing physical damage to the vehicle, so it is not likely it was the cause.

I can see why the alarm went off. When you opened the door with the key, the alarm was still in the engaged mode, but it never got a signal for authorized entry as it was frozen without the battery to power it. As soon as you jump-started it, it powered-up and was triggered by opened doors and trunk or hood.

vlad_a

Glad to help eliminate another "manual" task from driving the RX. In my IS300, I manually switch the lights on or off, but I let the RX do its thing. It is one of those cars that drives itself.

RXSF

If you left a door open or not fully closed, the headlights will not turn off after the 30/60/90 second delays