Help needed - Gen 2 Prius Linear Valve Offset not learning

Matthew Mobile Technician Bartlett, Illinois Posted   Latest  
Question
Braking
2005 Toyota Prius 1.5L (1NZ-FXE)
C1345
C1358

I diagnosed a bad ABS brake actuator assembly on this car. The shop replaced it but could not get the linear offset learn done with their tools. They called me back to do it with Techstream. I cannot get the procedure to complete. Sometimes the lights stop blinking after less than a minute, one time it made it all the way through, but the warning light never changed frequency. One time it set C1256 for accumulator pressure. The accumulator pressure did drop low and the pump runs quite a bit when the pedal is used. Could this not be completing because of air still in the system? The shop did the scan tool bleed, they said it took around 40 minutes to complete. Voltage never drops at the fuse box when doing the procedure, I had my maintainer on it. Any tips here? As of right now I am planning to bleed this thing myself tomorrow and retry, but would like to know what else to look for. Thanks in advance!

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Robert Diagnostician
Ballston, New York
Robert Default
 

Was the accumulator replaced also? I have had to replace both halves of those electro mechanical assemblies quite often. It’s common to replace the valve assembly and have the other part failed causing the pump to run due to low accumulator pressure. It develops an internal leak. Once the accumulator pressure is difficult to keep charged it will not complete the offset learning. Now we recommend…

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Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

I will check tomorrow, I believe it was an assembly with the module, hydraulic unit and both motors.

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Matthew Technician
Lawrence, Massachusetts
Matthew Default
   

I agree it's a good idea to first try to rebleed the system with the Techstream. Was the assembly a new genuine Toyota unit or used? If it's used see if they can find out the year of the donor car. I've herd there is a difference between the early Gen 2 units (04-05) and the later years despite part numbers being the same. I always try to used like years when replacing them. Also if a used unit…

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Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

It is an AM reman. We didn't want to go used because of high failure rate, but dealer part was pretty expensive. This car has been a nightmare for the shop... they replaced the hybrid battery. It had an isolation issue after two weeks. Replacement pack had another isolation issue. Owner of the battery company personally came from two states away with another pack to fix the car. The ABS light…

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Rudy Technician
Montebello, California
Rudy Default
 

It does not take 40 minutes to bleed this car,but it must be done in the proper sequence. If using a Snap-on tool the sequence is listed incorrectly. If using an Autel tool,the procedure will not complete. Techstream has to be used to bleed it properly and it takes all of 15-20 minutes tops. I dont know if air is your issue,but I definitely bleed it first.

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Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

Thanks Rudy, they used Snap-on. We are going to do it Monday with the Techstream.

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Joel Diagnostician
Soquel, California
Joel Default
 

exactly snap on does not mention to remove , or re install the abs motor relay 1 and 2 , before satring bleeding the front and re install them to start bleeding the rear brakes , for the linear valve calibration we had issues too , I believe there is something missing in the tech strem too when doung that calbibration we had the issue before we when to tis , info and found there the missing pice…

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Richard Technician
Virginia Beach, Virginia
Richard Default
 

Have completed this multiple times with an Autel 906bt on a Lexus. Friday, replaced a skid control module on a RX400H and it went right through. Had a LS460 that would not finish the relearn because the actuator had a bad solenoid ,had originally come in with a burned up accumulator pump. When we replace these, we always use factory parts.

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Samuel Technician
Somers Point, New Jersey
Samuel Default
 

In my opinion, the bleed process is key...I however, did use a Snap on product combined with details in alldata and all went well for our shop. Hope removing the air solves your issue!!!!

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Richard Technician
Virginia Beach, Virginia
Richard Default
   

2 more notes to add. When you are bleeding, make sure that the reservoir is being replenished as this process moves a lot of fluid. I would also recommend using a battery pack or maintainer because if the voltage goes to low, it will not finish. Especially because this vehicle uses a lawn mower battery:).

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Sean Technician
Cincinnati, Ohio
Sean Default
 

I have a friendly shop that called me about that exact code on a Prius and they couldn't get it to bleed, they have an autel. So I packed up my verus, and my pressure bleeder and doing them back to back worked for me.

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Matthew Mobile Technician
Bartlett, Illinois
Matthew Update
 

I just wanted to give an update. The accumulator is bad on the reman unit. The shop will be replacing it, I will get back with another update when it is fixed.

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Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

New module fixed it. Accumulator pressure was dropping too low. Thanks for the help!

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