Good day to everyone. I have an obscure problem on my 2014 rx350/160k on it. I appreciate any input you might have.

exhibit1: after driving ~1h at a speed ~100kmh steering light popped up, check power steering msg showed up and nav system restarted. Thankfully engine did not stall i could keep driving, and i got back home.

exhibit2: following the trip while backing up to my driveway i felt power steering getting lost momentarily (i.e. wheel was no turnings smoothly but rather with statters) and nav screen was blinking and finally restarted. I tried backing up several times and could reproduce problem at every try. 30min later i tried again and could not reproduce it anymore while backing up and everything was back to normal.

i am a bit hesitant to drive long distances now.

thinking i have is that electric steering motor is slowly dying while causing spikes in power draw from battery and thus restart of the infotainment system. What is puzzling why it shows up after long drives only, is something overheating…?
i will keep on trying to find root cause.

Did anyone have a similar problem?
thanks for any input!

 

Does sound like an electrical/electronic problem.

Let us start by history ... any work done that might involve wiring, attaching removing connectors etc.

General. How healthy is your 12v battery. Terminals clean and tight?

A visit to dealer or someone who knows the electronics of the vehicle would be good as there could be a communication problem between modules. Based on wiring info they can triangulate with failing components to a probable cause.

Salim

 

Thanks for the reply Salim. so simple but it did not occur to me to check battery connectivity to begin with. Positive terminal was indeed a bit loose. I tighten it up now and I will test it over the week and report back. Answering your questions: battery was replaced 2020-2021. it holds charge well. car off 11.9V, car on 13.7V. We did change ecu (it died because it was shorted when top of broken muffler blew heat on charcoal canister which sits right above it and melted the wires). I get that a lot of things can go wrong after but pointers are appreciated when it comes to investigation. Given that problem with steering comes sporadically it might be time consuming to even reproduce it for dealer/garage thus I am trying to see what I can check when I have it happening again to identify root case. (There are no codes stored otherwise in the system, rack and pinion seems to be in ok state/not leaking/nor I had any liquid on the floor, i dont hear any noise coming from steering column either when problem happened. like i mentioned the only unrelated effect was infotainment system restart).

 

Shooting from the hip, the battery seems weak. Tightening the terminal may be able to revive it [better charging] and I would suggest have it load tested in few days. Middle of the run batteries last 2-3 years and the better: 5-7, but it all depends on climate and use. I would suggest replacing it, before investing in debugging. Ah the test result will tell you better.

Another missing link is how long ago was the ECU replaced before you observed the electronic oddities. And how was the ECU sourced? These may be moot points, if the problem goes away.

Salim

 

I agree that your battery seems weak. Keep in mind that regardless of age, any battery can fail at any time.

 

Another thing you could check is the grounding system. Your symptoms reminded me of GM pickup trucks that are a bit notorious for having power steering issues only because the $0.02 ground straps GM uses turn to dust after 5 or 6 years of driving on salty winter roads. Not sure where the grounds are on this RX, or if they are prone to failure or need of maintenance, but just a thought that occurred to me as sounding similar. In any case, its relatively easy to test, use a volt meter with one side on the negative battery terminal (not the cable, the post itself) and the other side try on the engine, frame, and other metal body parts. The voltage should normally be close to 0V (as all these parts should be well connected to the negative battery terminal with no or minimal potential voltage between the two). But if you see something close to 1V or higher, then you have a ground issue (the volt meter is carrying/showing current because the existing ground straps are rusted or loose and not fully able to carry the current itself).

 

- Somehow I forgot to mention ECU was replaced 2.5y ago so I would hope it is not related.
- After tightening the positive terminal and driving for a week I have not observed symptoms yet. Will see what the other week brings.
- Tested for grounding issue and voltage is indeed around 0 (a few mV). I will test a battery to be safe in the coming weeks.
Will report how the situation evolves. Thanks for replies everyone.