Prius Brakes - Understanding The Brake ECU
Regenerative Toyota Prius Brakes
The government is currently investigating Toyota Prius brakes which are at the center of Toyota’s latest recall.
The braking system in the Prius is controlled by an ECU or Electronic Control Unit. An ECU is simply a metal box with electronics inside of it that gets information (input) from various sensors and then transmits an (output) to other computer systems in the vehicle.
The regenerative brakes are part of the Prius charging system, which reclaims voltage like a generator does. A software glitch is what is supposedly the problem and Toyota dealers will begin being informed of the intent to recall about 100,000 Toyota Priuses in the US. Usually when a problem occurs in the ECU a fault code is stored so that further diagnostics can be performed to determine the software upgrade that could fix it.
The Prius brakes are programmed to switch between friction and regenerative braking when certain pre-determined programming conditions have been met. The CPU will interpret the data and then send signals through the communication bus to various modules to perform set tasks.
The sudden loss of braking occurs when the Prius is driving on a rough road or in poor weather conditions which may cause the brakes to pulsate as the system switches between regenerative and standard braking.
The switch occurs when the vehicle speed reaches a set MPH, and a delay occurs when the brake system changes over from regenerative to standard.
Some owners of the popular Prius have been aware of this brake problem for years, and some of them have documented the problems despite getting help from Toyota.
Heres what one of our readers shared:
“I have a 2007 Prius and I had thought my car just not good in the winter. It has been getting progressively worse. Last month in the ice storm, the brakes didn’t hold. I pulled over on the side road where we live, called my husband crying to come and get me. He brought our RAV4, and he drove the Prius home. It was a very scary feeling that the brakes wouldn’t hold on slippery roads.
I reported this problem to the NHTSA and was told there are other complaints being called in. I bought my Prius thinking I was buying a well made Toyota. I hope Toyota can fix all the safety issues with the Prius.”
Ray LaHood, the Transportation Secretary has opened investigations in regards to these issues surrounding the Toyota Prius and went so far as to say owners should park their Toyota until a final repair is deemed sufficient. He then revised that statement to say owners who are experiencing problems should contact their local dealer immediately.
Improper braking can occur in the Prius while traveling on icy roads, and could be linked to electronic problems with regards to the vehicle speed sensor which is what the vehicle uses to determine when to switch from regenerative to standard braking. All of this information should be retrieved from the ECU and Toyota should be able to publish the solution to the fault codes that are being thrown when the braking problems occur.
