Brake, ABS, and VSC after HV Battery replacement

It's really easy. You don't disconnect the battery to bleed the brakes. You have the car ON, Techstream connected, and you say you'd like to bleed the brakes, and you do what Techstream tells you to do.

The people with the bad stories were trying to do other kinds of brake work, without Techstream, and they were disconnecting the battery hoping to avoid unplanned interactions with the brake ECU.

The one thing that can be frustrating with the Techstream brake bleed really just depends on what dongle you're using Techstream with. I had one before that loved to "lose communication with vehicle" about 85% of the way through the bleed procedure. Took me three or four tries (ok, once more from the top) to finish it. Used a different dongle last time and didn't have that issue.

 

Thanks for the info, I'll have to work up the nerve to try it. Is there a way to skip some of the brakes and just bleed the problem one? I think I'd prefer to do that first instead of risking doing something wrong with the brakes that seem to be working properly.

 

I skipped all of them once, when I knew I had no air in there and just wanted to get rid of a C1451. Lying to Techstream didn't fill me with remorse really.

 

If I remember correctly, one of the options in Techstream is to just bleed a single corner of the brake system. Also it's not a bad idea to have a battery charger going on the 12V battery while doing the work.

Posted via the PriusChat mobile app.

 

I don't remember a single-corner option, at least not in my version of Techstream and my version of car.

I get choices for a shorter bleed (for work on wheel cylinders and brake lines) or a longer bleed (following work on the head-end stuff).

But when Techstream tells me "go to such-and-such corner, open the bleed valve, wait for bubbles to stop, close valve, click Next", I don't feel bad about just clicking Next, if I've got no reason to bleed that corner.

 

Maybe that's it. Might be remembering another car altogether.

Posted via the PriusChat mobile app.

 

Sounds good to me. Do I need an assistant to keep slight pressure on the brake pedal, or does Techstream use the brake accumulator unit to pressurize the line? From one of the postings I read here, it sounded like the bleeding might be more conventional (having an assistant press the brake pedal) and Techstream just monitors and gives instructions.

 

Somebody with more direct Gen 2 experience can give you the details for your Gen 2.

I know on Gen 3, there are parts of the procedure where you need to pump the pedal, and parts of the procedure where the system pumps for you. Those are bleeding different parts of the hydraulic circuit, including the ones that do the normal braking and the ones for fail-safe braking. The Gen 3 'full' bleed procedure does the rears (using the pressure accumulator, no pedal pumping), then the front fail-safe circuit (pedal pumping), then the stroke simulator (pedal pumping), then the front lines again (using the pressure accumulator, no pedal pumping), and then does some calibration and six rounds of emptying and repressurizing the accumulator.

I have faked my way through the pedal pumping parts by using a brake pedal holder to press the pedal, reach for the bleeder, open it, close it, climb back to the car, release the holder, reapply it, reach for the bleeder, open it, close it, climb back to the car, etc. It's a lot faster with an assistant.

 

Thanks for the reply. I'm sure that I can find an assistant, just not sure how well I can get them to not press the brake pedal too hard. I like the idea of the accumulator providing the required pressure for bleeding the four corners.

I'll look through the Gen2 postings again, but that's what discouraged me last time. No one gave good step by step instructions like the Gen3 owners do.

 

You have to complete all the parts of the sequence, the accumulator-provided parts and the pedal-pumped parts. For the two front corners, there's both a pedal-pumped part and an accumulator-provided part (in separate steps). At least that's how Gen 3 does it. I would imagine Gen 2 is similar, as it also has a fail-safe hydraulic circuit for the front brakes.

 

I never followed up in this thread about what the mystery ABS 42 and VSC 45 blinks mean.

More here.