MM 0 1 7 Brake Fluid Change

** I think I've got it ** ??
I looked for codes using the sometimes trusty AP200.

Found a code in the ABS/VSA modue - U0418-68 (ESB/EBB failure).
I cleared this code and no joy.
Then,
Also found the same code (U0418-68) in the Electric Servo Brake System.
I cleared this code, and voila !!

I now have a clean instrument panel. I have every reason to beleive that this was due to the expected result of flushing the fluid while the vehicle was ON. Time will tell if this remains good going forward.

If true, then the service documentation is wrong when stating that the 3-second brake depression will clear the indicator.
I would now recommend against a DIY'er flushing with the brake pedal in the ON mode (unless thay are equipped to clear DTC codes). If you can't clear codes, use the procedure described by @leop in post #58 above.

 

If the brake fluid is not flushed with the Clarity turned on, the fluid in the servo unit will not get flushed. Note that the servo unit (tandem motor cylinder) provides all of the fluid pressure when the system is on and working correctly. The master cylinder attached to the brake pedal has the fluid passages blocked off when the system is on and the pedal force simulator provides the brake "feel" to the pedal. When the system is off, the master cylinder blocking valves are open (and the valve to the pedal force simulator is closed) and the fluid pressure is provided by the brake pedal attached master cylinder. Thus, when the system is turned off, the fluid in the master cylinder is exchanged when bleeding.

Note that the upper brake fluid reservoir is connected to both the master cylinder and the servo (tandem cylinder) unit. Also, when the system is on and working correctly, pushing the brake pedal to bleed the brakes actuates the tandem cylinder servo and the servo unit moves the fluid to the caliper being bleed. The pedal actuated master cylinder just pushes the pedal force (feel) simulator piston as any fluid movement to the calipers is blocked off by the closed master cylinder cut valve.

BTW, I am glad that MrFixit found the correct trouble code to reset. I will note that in case I have any such issues in the future. I suspect the the trouble code may be related to the upper and lower hydraulic pressure sensors sending unusual values as the pedal is pushed when bleeding with the system turned on. I recall reading about a similar issue with the hybrid Accord brake system when exchanging the fluid.

Another two cents worth, LeoP

 

@Clarity_Newbie - I assume you didn't encounter this with your vaccum method (presumably because you weren't replacing fluid with the vehicle ON?)

@MrFixit

Correct. I did not encounter any error codes on either Clarity.

Actually, I did the on/off since that is what is recommended for this system...hence the "around the horn twice" and should have noted the on/off as well as following the sequence referenced by @Fast Eddie B as far as the order of extraction. Feces happens.

Worked well...or at least seems to have. 10,000 miles strong between both vehicles with no issues.

Good luck!

 

I did my 017 service yesterday and followed the same procedure as @MrFixit. Everything went as expected and the brakes work fine. But, like @MrFixit, the "Brake System" indicator was illuminated and didn't clear when I put the car in "On" mode and held the brake pedal for 3 seconds. I used both Vgate and Autel to check for error codes, including in the ABS/VSA and Electric Servo Brake System modules, but none were triggered. I turned the car off and on multiple times, drove it, and checked for error codes multiple times. I decided to wait a day to see if the indicator would clear. Today, the "Brake System" indicator was no longer illuminated. I think it's odd that the indicator was triggered without any error codes being recorded but, at this point, the job is done and everything seems to be fine. BTW, my tires seem to be holding up well: 25K miles with at least 5.5/32 of tread remaining on each one.

 

Very odd...

I wonder if there are multiple ways to check for codes? The way that I checked (using Autel) was through the diagnostics menu where you can select the desired susbystem (as we do with the Electric Powertrain, when checking battery capacity). On the same sub-menu (only for the ABS/VSA, and ESB/EBB modules) where you can select "Live Data" there is an option to check for codes. That is where I found the U0418-68 codes that cleared the problem. This same sub-menu lets you clear codes that it finds.

It is good to know that simply waiting seems to clear the code. Sometimes codes are persistent and once triggered will never go away without clearing them, Others will automatically clear after a prescribed number of drive cycles as long as the fault is no longer present. I am guessing that this one clears after a few drive cycles which woud be consistent with your experience. I was not patient enough to try that, and thrashed around until I happend to find the code.

 

That was one of the ways I checked for codes, and found none.

What I find particularly odd is that the "Brake System" indicator was cleared as soon as I powered on the car the following day (i.e., before I drove it). That indicator was still illuminated when I turn the car off the prior day. Maybe a certain number of on/off cycles is needed to clear it, and I landed on the correct number the following morning. Hopefully, we'll get more data as additional DIY members replace their brake fluid.

 

I got the MM017 code a week or so ago on my '18 Clarity Base (purchased new in 03/19). No way I'm changing brake fluid in a vehicle with 13K miles.

Reset the reminder.

Planning on purchasing a VW ID.4 Pro S AWD later this spring, so won't be spending any money on the Clarity. It's been a great vehicle for the small number I've miles I've put on it. It definitely opened the doors for going full EV for my next vehicle.

 

I replaced my brake at 7500 after three years of Covid limited driving. Time is more important than miles. The fluid is much clearer now.

 

So mine just flashed the A017 code and I called the dealership near me and they quoted $159 just to do the brake fluid replacement and another $70 for oil change and tire rotation.

Could the brake fluid replacement be done by a dealer shop like Midas, Jiffy Lube, or Valvoline? What are the risks? Would appreciate any thoughts. Thank you.

 

The risk would be that they wouldn't actually do it and still bill you.

 

I did hear stories like that before.

 

See this post by the great (but long absent) @KentuckyKen. The risks are that a non-Honda shop might not understand the more complicated procedure for the Clarity's braking system and leave some air in the lines. Many forum members have successfully performed the procedure themselves--it's not rocket science, just a little different than a 1965 Mustang. This post by the wonderful @MrFixit includes the PDF for the procedure.

 

For this car, I wouldn't bring it to outside shops for brake fluid change. They wouldn't know how to flush the 2nd reservoir.

 

Something kind of strange, don't know if this happens to everyone. When I click on the link that you provided,

http://www.insideevsforum.com/community/index.php?threads/mm-0-1-7-brake-fluid-change.9598/page-3#post-149377

It takes me to that thread, but if I look at the top of the page I am no longer logged in. I found this out because when I click on the attachment PDF file in that thread I get a message that I am not logged in. I tried logging in while I was on that page, it seemed to accept my password, but after logging in when I look at the top of the page it still says that I am not logged in, so I can't download the attachment. If I go back to the main Clarity page I am still logged in, so it looks like I am not actually getting logged out, it's just on that older thread it appears that maybe older posts were moved into some type of archive or something where our logins don't work. At least mine doesn't.

 

Glad I read this thread. I'm at 3.5 years ownership and 56,000 miles and no sign of the A017 minder. There must be something in addition to time which influences the brake fluid change interval.

 

Sorry I didn't test that link before including it. The same thing just happened to me but I found a workaround that I don't understand. I googled for that file, google took me to the same InsideEVs forum page (I was automatically logged in), I clicked on the link and it let me download the PDF file. I attached it to this message--hope it works for you.

 

The Google method worked for me also, and I think I figured out why. The pages on this site are https:// (encrypted) as is the older thread. For some reason clicking on the link to the older thread goes to the identical address except that it is http:// (unencrypted). So the site looks identical but it's unencrypted and the forum login doesn't work.

Another workaround that demonstrates this is to click on your original link, then after landing on the page where you are not logged in, change the address at the top of the screen from http to https and press enter and now you are logged in. Interesting. But anyway thanks for posting it.

@MrFixit do you know where the document came from and if it's for sure for the Clarity? Other than the PDF filename there is nothing on the document that I can see indicating where it's from, maybe another model of Honda? Even so it's probably still applicable but it would be nice to know for sure.

Also it's not clear what they mean in the brake fluid document by "the ON mode". In the Clarity owner's manual it sometimes uses ON capitalized to indicate pressing the power button twice without pressing the brake pedal. ON mode runs off the 12V battery, and it's even more battery draining than ACCESSORY mode because the entire 12V system is powered up including all of the dash lights, and also the DRL's which would really drain the 12V battery unless you use the parking brake trick to keep the DRL's off.

For a lengthy procedure like brake fluid change it would be preferable to be in READY mode to avoid running down the 12V battery like you would in ON mode. Maybe that's what they meant, after all even the owners' manual is inconsistent with this term. In some places it uses ON to refer to that specific mode, for example:





But then in several other places it uses the term ON mode when the context appears to be READY mode, like in this example:




It's really a shortcoming in the owner's manual that it is not consistent with the use of this term because it's such an important distinction between ON mode and READY mode.

 

The document was sent to me by another Clarity Forum member who had access to Honda's online Service Informaion System.
He sent me a screenshot entitled "Brake Fluid Replacement 3570". For convenience, I just pasted the screenshot into a .pdf document, so the filename was my own. The screenshot did include a URL as a footer beginning with https://www.in.honda.com....' which is a legitimate entry for dealers into the Honda service network. I did not include the URL in my pdf for fear of possibly incriminating the person who provided it.

 

I can confirm that document 3570 is the correct document number for the Clarity, and the content looks the same as is on the Honda website. There is also a longer document describing "Electric Servo Brake System Bleeding", but that wouldn't be needed for brake fluid changes.

The power mode is confusing. Here are some other mentions:

1. "Turn the vehicle to the ON mode." -- service manual for some procedures
   
2. "Turn the vehicle to the READY TO DRIVE mode." -- service manual for other procedures
3. "To check if the readiness codes are set to complete, turn the vehicle to the ON mode, but do not start the engine." -- service manual on checking readiness codes.

The service manual has many instances where it says to use "ON mode", and many others others requesting the vehicle to be in "READY TO DRIVE" mode.

I'm guessing that in the cases that it says "ON mode" without any other note, it'd be OK to also be in the "READY TO DRIVE" mode, but I'm not sure.

Also pay attention to the notes at the top, which mentions that it's normal that the BRAKE SYSTEM indicator turns on when the fluid is replaced while in the ON mode.

 

Great, thanks.

I noticed that also, I am guessing they are just letting you know that when the fluid level gets low during draining the brake warning light will come on, but that this is expected, and it will go away as soon as brake pressure is applied.

I tend to think so also, they likely mean READY mode in all of these cases. The root cause really is that the term ON is going to be inherently confusing, because most people (including technical writers apparently) tend to think of turning an electric vehicle "on" and thus commonly use that term to mean making the car ready to drive, so it tends to become synonymous with READY. Unfortunately there also exists a specific non-driving mode named ON. Maybe the word standby would have been a better name for this mode instead of ON. But it's not really Honda's fault because ON and READY seems to be standard terminology in the hybrid world, I'm not sure about EV's? I assume the intention was to imitate the terms Accessory and On modes in gasoline cars, i.e. in a gasoline car turning the key to ACC then ON without turning it to Start.

Not helping things is when it's a poor translation to begin with, like this classic example in the brake fluid document:

"Pump the brake pedal slowly during the vehicle to the ON mode". I assume "during the vehicle to the ON mode" is simply a poor translation which should have been, "while the vehicle is in ON mode"