Breakers

Hi all,
first post, first RX. I recently took possession on a 2015 RX350.

I seem to to be having issues that the dealership is having problems tracking down.

They have had the car for 7 days now with no new information

what it does, first thing in the morning, car is completely dead. Remote doesn’t work, open door with the key, put key fob by push start and the car powers up. I then start the car and the alarm goes off.

After this happens the car is fine all day. It does seem to only fail in the morning when the temp is under 50 degrees.

Here is is a link to YouTube video that I showed techs.


thanks guys!

ColAngus

Weird. The battery definitely is not dead because it has enough juice to crank and start. Do you have a second fob? Try replacing the batteries in all fobs.
It seems to be failing to recognize the fob correctly. Maybe you didn't get the correct fob and they only partially mated the replacement fob?

Breakers

Thanks for the reply,

Only have 1 fob, put a new battery in the car and twice in the key fob.

This only happens after it’s been sitting all night, although it Will sometimes fail when it is cold and rainy but the alarm doesn’t go off and the mpg does not reset.

When I press the button to shut it off I can tell if it will fail again immediately as the seat and steering wheel doesn’t retract.

Droid13

My gut reaction is that its a temperature related short in the ECU. Electronic components at operating temp usually sit nicely above 100F. When left to sit in the cold, a tiny connect point fails as the materials contract from the cold (and why spacecraft use internal heaters or die). If so, these things are hard to officially diagnose without replacement to see what happens because even a few seconds of operation can warm the circuit boards enough to close the short.

Breakers

Just have to figure out which of the 32 or so processing units is causing it. Lol

Non

This will be a tough one to figure out.

One of the ECUs must have a malfunction that sometimes goes away (FYI you open a short, not close it

I would try to narrow down which ECU is bad, start by gathering as much data as possible.
For example, what happens when you get in the car and press the start button with your finger? Does the display light up and ask you to put the fob to the start button? Or nothing happens?

Non

So you're saying that every timer this happens the MPG and the trip computer reset?

Breakers

I’m not sure about the trip computer but both miles per gallons reset.
It's completely dead until I put the fob up to the push button.
I just heard from the dealership I bought it from and they are giving up. ( not Lexus) but they did call 2 Lexus service centers and they had not seen the issue either.

I cannot believe that it didn’t fail after over 7 days of them having the car.

afpj

Has it been hooked up to techstream and scanned for codes?

Breakers

Dealer said no codes set, that they had the software to check that stuff. But I’m seeing that options that work before don’t react the same. Like the lights coming on when you walk by the car, that no longer works.

Clutchless

Lexus has travelling tech specialists who investigate such problems that dealers are unable to diagnose. Usually called Zone Techs or similar. Ask the dealer or call Lexus corporate about having one look at your vehicle. Most of the car companies have such specialists trouble shooters.

heshamos

Have you washed the engine bay lately? It sounds like a moisture in a place that's not supposed to have any!

Breakers

So I’ve got this thing down a bit more.

This is morning check awd, swerve and ! Came on. Ran codes:

c1432 - steering angle sensor power low
c1297 - steering angle sensor.

Saved codes:
u0208- lost comm with seat control a
u0142- lost comm with body control module b
u0155- lost comm with instrument panel cluster
b15f8- d seat Ecu vehicle information reading/writing process malfunction
b15c4- srs communication error.

Crazy symptoms that that only happen with temps below 50 and rainy/dew around. Car has to be parked in the shade, morning sun will dis the issue.

Anyone know where the body control module resides?

thanks, no didn’t wash anything under the hood. Lol

raylor4

Just a wild guess...Rodents chewed the wires? Doesn't tie in with the temperature correlation, though.
Ray A.

afpj

Rodents...that would make sense of multiple unrelated codes. Still suspect battery, unless it was load tested to be good. Just because it cranks over doesn't mean it's a good batt. Electrical connections (ie battery cables) nice and tight? Was this vehicle a prior flood car?