BSM Error

BSM failure only occurs at 80 degrees (temp) +/- 3 degrees. All fall, winter and spring works great. Summer fine until it as I said above. Turn engine off, restart and it fine for a couple minutes. Yes it has been bumped. Also after it rains, even though not driven, I go to back out and mostly that left side lights up on the dash as if there is a possible obstruction. I guess it just dries out after a while. Toyota wants to replace 3 sensors at around 4k. Funny, I am old enough to remember FM being an option. I can live with it.
Thanks for any thoughts!

 

Well, for starters there are only two sensors to the BSM system, so there is a misunderstanding somewhere. They are hard to get to but check the connectors for any corrosion. Unplug and look inside the sensor on the bumper and the wire/connector in your hand. This is where I would start. May require a mirror.

After that I would remove the left one and take it apart. Removal is difficult. There is some intriguing assembly inside that could be temperature dependent. Since your system is not working, I see no danger of doing more damage in doing so.

 

My bad. You are correct. The 3rd sensor is the Steering Angle Sensor which was replaced.
The BSM does indeed work but only below 80 degrees. To your point though if I wish to resolve it I am going to have to get into it. Thank you for the reply!

 

On a hot day try applying some freeze spray all over the left BSM sensor. It could take some time to have an effect within the black plastic box. This would be to "prove" where the problem is.
Such as:

$30 MG Chemicals - 403A-285G 403A 134A Super Cold Spray, 285g (10 oz) Aerosol Can

MG Chemicals - 403A-285G 403A 134A Super Cold Spray, 285g (10 oz) Aerosol Can: Freezing Spray: Amazon.com: Tools & Home Improvement or anything else you have to counter the heat.

Since the case has probably been compromised it will most likely completely fail someday.

I've taken a BSM sensor apart and find the simplicity/ease of their construction intriguing. Found it on eBay for less than $100. In this particular case I did not care if it worked as I was looking to educate myself about them and knew it was sacrificial. A replacement may require recalibration by a body shop.

Why was the Steering Angle Sensor replaced?

 

Jump in my friend.
I'd study the link below before I spent $4,000.
Something tells me the dealership is "throwing parts" at it. Not actually diagnosing the issue.

https://www.ttguide.net/park_assist_monitoring-380.html

 

I will read the Guide asap. I agree on throwing the parts as well as hitting the number. Use to be in that game only medical. I had thought of trying to cool the sensor but was not sure how. Thanks for the AZ. link. Ah the steering angle sensor. Came out the next morning and the battery was stone cold dead. Put a charger on it…….started it and had the steering angle sensor error on the dash screen. Ordered the Super Cold spray. Won’t deliver until next week. Going to start there. Thanks

 

If you need any wiring diagram help, let me know.
If your batter was dead, you might need to do some system checks.

Did the dealership happen to right down any codes?
It would help if you knew if/what they were.