Starting issue

[pdx19751]

I have had several instances of being unable to star my vehicle. Recently stopped in traffic for about 20 minutes and vehicle would not start after numerous attempts. Tried shutting off the power, taking foot off the brake, then repeating the starting process. After about eight of nine tries it finally started. Happened again today when refueling. Foot on brake, pressed start, all power comes on but engine doesn’t start. Again, it took several tries at repeated starting process before the engine engaged.

 

[ShottsCruisers]

Is it trying to start via the normal process? (Hybrid motor is the starter) Or, does it sound like it's cranking like a typical car? The 700h has a typical 12V battery, starter and alternator. So if the hybrid system fails it can start and operate like a normal non-hybrid vehicle. ???

 

[pdx19751]

Not turning over like a regular car. Nothing happening at all. Not sure why the alternator isn’t kicking in to start it. When I push the start button nothing happens.
I have a service appointment scheduled but am afraid Lexus won’t be able to duplicate the problem because it seems to be so sporadic.
But it was pretty unsettling to be sitting in traffic in a brand new Lexus not being able to move.

 

[ShottsCruisers]

But it was pretty unsettling to be sitting in traffic in a brand new Lexus not being able to move.

Whoa! Are you saying you have been driving...and then in traffic it shuts down and won't start again?

 

[DWIESE]

Whoa! Are you saying you have been driving...and then in traffic it shuts down and won't start again?

This is not happening in my LX700h but it did happen in my LX600. May not be the same issue but dealer had me put key fob next to start/power button to reconnect. I never knew why it happened but that did work.

 

[pdx19751]

No, I turned the car off for about fifteen minutes then tried to start it again. It took at least five minutes of cycling through the start process before it finally started again.

 

[ShottsCruisers]

Ahhh gotcha. While I am no mechanic my gut says this is something very simple. An easy catch for them to find.

 

[pdx19751]

Thanks. I hope so. Still not sure why the alternator didn’t kick in and start it since the hybrid didn’t seem to be working.

 

[ShottsCruisers]

Cause the hybrid battery and system are good. Otherwise you'd see messages and codes thrown. They end up starting your car. Somethings up communication or relay-wise from the start button (etc) to actual starting. Gotta be an easy find.

 

[CRBRSLX]

I have had several instances of being unable to star my vehicle. Recently stopped in traffic for about 20 minutes and vehicle would not start after numerous attempts. Tried shutting off the power, taking foot off the brake, then repeating the starting process. After about eight of nine tries it finally started. Happened again today when refueling. Foot on brake, pressed start, all power comes on but engine doesn’t start. Again, it took several tries at repeated starting process before the engine engaged.

I traded my in my 2025 LX700h after 5 months (5,300 miles) and CarFax updated the service history the next month (5,700 miles) that the Lexus dealership replaced the starter and did other work. Good luck and hope you get it fixed.

 

[ShottsCruisers]

Makes no sense. The engine does not get started by the traditional starter. It gets started by the electric motor. ONLY does the starter start it IF the hybrid system/motor fails.

 

[CRBRSLX]

Makes no sense. The engine does not get started by the traditional starter. It gets started by the electric motor. ONLY does the starter start it IF the hybrid system/motor fails.

I apologize it was the alternator and seven (7) other services that were done. It was not a starter. Still not a good thing for a vehicle that had less than 6k miles and six months of driving.

 

[ShottsCruisers]

Wow! I'd love to see that service/warranty receipt.

 

[CRBRSLX]

Wow! I'd love to see that service/warranty receipt.

What is interesting is that I traded in the LX700h Overtrail and picked up a 2026 Toyota 1794 and it had a defective digital rear view mirror not picked up during PDI. It took 2 service visits and them keeping the vehicle for 6 days to repair. The part was approximately $2,300 and whatever warranty labor. So much for Lexus and Toyota quality.

 

[pdx19751]

Took the truck in to Lexus today and they replaced the 12v battery. Service tech told me that turning off the engine and running accessories for 20 minutes likely ran the battery down. He said that whenever the engine is not on all the electronics run off of the 12v battery. I was under the impression that the hybrid battery would keep the 12v charged. He said that even using the 24kw plug in the back will run off of the 12v if the engine isn’t running, and that the hybrid doesn’t really communicate with the 12v at all. I was under the apparently mistaken assumption that the 12v was only used for starting the car.
Not sure how Tesla can run the air conditioning, etc. for extended periods, but Lexus can manage to operate the electronics from the hybrid system.

 

[henke]

24kw plug in the back will run off of the 12v if the engine isn’t running

Sounds like a load of bull. You can't even power that AC plug if the engine isn't running.

I have run the battery dry a few times, and every time the engine did not start. I have never gotten the engine to start again just by waiting or cycling...

 

[pdx19751]

It will theoretically run with the hybrid charging the 12v battery but the car has to be on and as the hybrid depletes, the gasoline engine turns on to charge the hybrid battery.

 

[ShottsCruisers]

There is ONE reason this vehicle has a 2400-watt converter. HYBRID battery.

 

[ShottsCruisers]

Took the truck in to Lexus today and they replaced the 12v battery. Service tech told me that turning off the engine and running accessories for 20 minutes likely ran the battery down. He said that whenever the engine is not on all the electronics run off of the 12v battery. I was under the impression that the hybrid battery would keep the 12v charged. He said that even using the 24kw plug in the back will run off of the 12v if the engine isn’t running, and that the hybrid doesn’t really communicate with the 12v at all. I was under the apparently mistaken assumption that the 12v was only used for starting the car.
Not sure how Tesla can run the air conditioning, etc. for extended periods, but Lexus can manage to operate the electronics from the hybrid system.

"henke" is correct. The AC will not power unless the engine is "started". Once on the outlet will power even if the engine does it's hybrid thingy...on and off then on and off, etc.

So the Lexus dude is wrong.

I am also almost 100% sure the 12V battery has nothing to so with starting. It's the hybrid motor that starts the engine. What powers the hybrid motor? Yezz...the hybrid battery.

 

[henke]

At the very least the 12v indirectly affects starting. You can't start the car if the computer systems aren't on, which are powered by the 12v.