We were driving 2015 450h with 2200 miles on a slight downhill grade about 50 mph. Suddenly ABS warning light, master warning light, and audible warning activated. The center console "Brake" illuminated and the information center displayed "check hybrid system". My wife attempted to pull the car off the road in a controlled manner but even slightly touching the brakes caused them to pulse, braking hard and then releasing. She finally got the car to the side of the road and shut the engine off. I then got into the drivers seat and turned the car on. The messages remained. Tried on an off, still the same. Tried brakes, the seemed functional. Since we were in a location that did not have cell service and it was an unsafe location to leave the car managed to drive it into nearest town.

Contacted Lexus for assistance. Friday around 5pm Pacific time. They were polite but not much help in arranging for alternative transportation. Closest dealer was about 2 hours away. While trying to figure out what to do, checked under the hood, found nothing.

Turned the car on and off about 10 times over the period of an hour. Without explanation, the car started with no warning messages. Dove the car another 200 miles since and it has now been at he dealer for over a day with no word.

I did see where a few RX350 models had reported a similar problem, but no 450h's.

At the time of the incident we were not using the PCS system (off) . I am wondering about that as well since the ABS might be tied into the PCS?

 

There should be fault codes that the dealer can read to help determine what happened. Keep us posted on their findings.

 

The service dept. called to say they cannot find any fault codes. The RX350s had the same problem. The dealer has reported the problem to Lexus and is awaiting instructions. Stay tuned.

 

Hopefully the problem is solved.

The dealer had the car for 6 days, drove it 80 miles, could not reproduce the fault. But, the health check showed code U0129 on the EMPS, combination meter, hybrid control, pre-collision, navigation system, PM2 gateway, and the blind spot monitor slave ECMS.

Code U0129 had information code 220, which means lost communication with brake system control module. TAS instructed the dealer to replace the Skid Control ECU part 89540-48471.

Within the first 500 miles I had also complained the navigation system was choosing very circuitous preferred routes, but thought I would wait until the 5000 mile service. The nav system also reported the same code U0129, and they believe it is related to the Skid ECU as well. The nav system now seems more responsive with the new Skid ECU.

At my request, the dealer provided me with all of the vehicle diagnostic report details, freeze frame data reports, and the TAS case number.

 

Cmonk -- thanks a lot for reporting back. It's always so much more helpful to hear about conclusions, and hopefully in your case, a positive one that allows you to now have many happy years of pleasurable driving behind the wheel of your RX450h.

 

Anyone else had this problem with their RX's?