After lights came on I took my 2010 Prius to the local Toyota dealer so they could pull the fault code(s). They called me last night before closing and emailed me the fault code the technician found, C1391. Based on code dealer says I need Brake Boost/Master Cyl ($1,018) replaced as well as Brake Booster Pump ($692) and the labor took total estimate to $3500+. I called Toyota Customer Assist Center to see if they could offer any relief as car is like 5-6 months over 10 years old but only has 81,000 miles on it. Toyota said they cannot do anything for me. I will now look for best prices on the two parts and install them myself. Has anyone got any recommendations as to where I can find out instructions on how to do the removal/install? I have never had to work on this car as up until now its been problem free but from what I read this repair may require computer/ software. Any guidance would be greatly appreciated. Thanks!
See the Repair Manual (more info) and, as an outline of how to fix this specific problem, service bulletin T-SB-0079-18 Rev1, “ABS Brake Warning Light On” (PDF), November 21, 2018. (The hyperlinks in the bulletin don’t work since it’s on NHTSA’s server, not Toyota’s.) You’ll need a Toyota Techstream diagnostic system to bleed the air from the brake system. If you’re following the service bulletin procedure, you’ll also use the Techstream system to check the calibration IDs (firmware versions) of the skid control ECU, and if updates are necessary, to install them.
I think I remember expressly agreeing not to when I signed up. Elektroingenieur probably did the same. But Elektroingenieur did put in the effort of constructing an entire wiki page documenting different ways of getting access to the docco, be it through TIS or local libraries providing free access, etc.
Well... my car has error C1391 and I don't want to pay $3500 and try to find a better solution. I bought a booster pump and the master cylinder removed from an accident car which means it is working fine. However you have to reinstall the ABS module in the cylinder you buy to replace and you need a scan tool to do that. I have Techstream software to check and clear the error but can't program it so after replacing and using the old ABS module... And the result is still error C1391. That means the Sensor system has a problem so I decided to change the Sensor to the original ABS module of the car. And the result is exactly the ABS module Sensor is the cause. Simply you just need to buy an old Master Cylinder and still working well, then remove and swap the ABS module Board. After installing them back into the car and use Techstream to check and reset the car. You need a Windows 32bit computer, buy a Mini VCI cable, download Techstream free software... you can use it to check and repair your car. I will give you the link if you need the software
