Help - 2015 Q70 Intermittent Brake Malfunction

[dalap83]

Here's what I expect is the final chapter: I got my car back last night after spending a week with a pretty nice Q70 loaner. My car was shiny clean, vacuumed, and working like a charm (they even found and fixed the door vibration brought on by loud classic rock music). The dealership at which I bought the car, Gregory Infiniti in Libertyville, IL, did it right; this is how to build a repeat customer. Gerard, the Service Consultant, and United States Marine Steve, the expert Infiniti-certified Journeyman Technician, managed to get the necessary approvals to order and install a new brake booster and pressure sensor switch even though they had not been able to replicate the issue. For the record, Steve wrote that his instinct was that replacing the brake booster and master cylinder would do the trick. At the end of last week, they called me and told me that they had found a leak in the master cylinder and as a result there was brake fluid in the brake booster. Now it has all been repaired, and as my toddler grandson said this morning, VROOM VROOM!

[BlackCat81]

I'm really glad to hear that. Thanks so much for your understanding and patience through the process. Have a great holiday!

[dalap83]

Unfortunately, the saga continues. Despite the dealer's attempts to fix my brakes, my car continues after a long drive to, without warning, require me to press the pedal all the way to the floor in order to stop. If I don’t immediately notice when the malfunction reoccurs, as it has dozens of times, I will crash into whatever or whoever is in front of me. I am afraid to drive my car.

[Ilya]

Curious if maybe the parts failed again in the same fashion as the originals...if there is fluid in the brake booster.

[reggiebrown40]

I'm going on a hunch that it's still the brake booster.

[k67p67]

Just curious...when the problem occurs, is it during straight-line braking or immediately after a turn?

[dalap83]

I have not noticed a connection between malfunction and turning but it appears to happen only after a long (90 minute) drive. And once it malfunctions, it continues to do so until I park and shut it down for a while.

[BlackCat81]

Well, like I mentioned when we talked, this repair was all a hunch based on symptoms you were describing. What will more than likely happen now is engineering will be involved and possibly come and assist or advise on a diagnosis. Really, the only left in the braking system that hasn't been replaced is the EBCM (electronic brake control module). I happened to see the car at work today because I was in trying to fix my M35 that decided to break a window regulator in the line for my coffee this morning at McDonald's when it was -5.

I thought for sure when I saw your master cylinder leaking we had it fixed for sure, but unfortunately that's not the case. Did it seem to be better or happen less frequently since I've replaced the above mentioned parts?

[dalap83]

It happened twice since you last saw it. And like the past few times before this, both recent times it started to malfunction only after I drove in heavy traffic for 90 minutes. That's the constant. I'm frustrated, as I'm sure you are. I sent a lawyer nastygram and copied Infiniti legal and corporate. I do appreciate the effort; the dealer sent someone to my home this morning to drop off a Q50 loaner and take my Q70 to the shop. I'm putting my faith in you.

[dalap83]

Day 9 without my car (this time around) due to this brake malfunction. Very frustrated.

[dalap83]

My letter:
This coming Monday will mark 3 weeks that you have had my car in your service shop, during this, the 6th time, you have unsuccessfully tried to fix my car’s potentially dangerous and deadly brake malfunction described below.

This week marked the one-year anniversary of the date that I traded in my Infiniti M-45x and proudly purchased this approximately $75,000 2015 5.6L Infiniti Q70. I was proud to be a loyal customer and purchase my third Infiniti vehicle. Now, you have had the car in your service shop over 10% of the time I have owned it. I am enraged.

I advised you that the malfunction occurs after 90-120 minutes of driving in traffic. Your service advisor told me this week that you have put 400 miles on the car during this visit alone. I am skeptical that this was all done during 90-120 minute drives in traffic. Anything less than that time is useless, and a waste of my property given how I have related to you my experience with this malfunction. My car is not to be used as your employees’ fancy shuttle. I demand that you maintain a daily written log setting forth the driver, the time and distance that the car is driven, and the results of the attempt to diagnose the malfunction/defect. I will check with you regularly, and expect that the log will be sent to me from time to time upon demand. Anything short of driving 90-120 minutes in traffic will not help to diagnose and fix the problem, given that that is the only trigger I have experienced each of the many times the malfunction has occurred. I will consider any use of my car other than to diagnose and fix this problem to be a violation of my permission to drive the car for this purpose.

Mr. Mauro, I am shocked that you, as the owner of Gregory Infiniti, have not had the courtesy and professionalism to call me and explain to me what you intend to do about this egregious situation and how you will use your relationship with the manufacturer to address this potentially dangerous and deadly situation resulting from their defective flagship product.

I am done being your victim. This day marks the day that I will begin to use my talents and resources to make my nightmare your worst nightmare.

[Ilya]

[mazz]

I suggest your solutions involve a man to man conversation and not a letter to the paper.
This is a bad break and you have big money tied up in this but if your interest is in resolution it will be done face to face not on a computer.
All the sympathy in the world from this chat wont get your car back in the garage.

[dalap83]

To his credit, Mr Mauro and his sales manager promptly called me to discuss the situation and promised to focus on a solution.

[mazz]

promptly? you have the patience of a saint ,3 weeks and 10% of ownership time aint prompt . nice guys don't win this discussion

[Ilya]

I suggest your solutions involve a man to man conversation and not a letter to the paper.
This is a bad break and you have big money tied up in this but if your interest is in resolution it will be done face to face not on a computer.
All the sympathy in the world from this chat wont get your car back in the garage.

I think the opposite.

Step 1: Letter
Step 2: Personal sit down

It's much easier to get your thoughts down on paper than it is in the heat of the moment (possibly) in a meeting. Not everyone is good in those situations.

[dalap83]

As a lawyer, I like to think I'm effective in writing and in person. They tried replacing the actuator, but I'll never know if that did the trick. That's for the next owner to worry about. I just returned home with my showroom-new replacement 2015 Q70. Infiniti stepped up and took back the defective vehicle and gave me a new one. Same options, but black instead of blue, and 15,000 fewer miles on it.

[Ilya]

Sucks that it came to that, but it is at least good to know that Infiniti didn't tell you to bugger off and instead owned up to it (whatever it is). Hopefully this one gives you no trouble like most of our cars.

[mazz]

That is a happy ending sorry about your troubles and the length of time it took but it should assure us you took the right path and Infiniti is capable of correct choice. Enjoy your new black car

[mikedamageinc]

Man i read this thread patiently waiting for the fix and and I find out you had to get a new car!? I'm having the same issue, replaced the master and no change, no booster or controller available on Rock Auto and I'm afraid to even ask the dealer.

Is there a way to disable ABS without affecting anything else to isolate the brake controller?

[VStar650CL]

Anything you do to disable the ABS (like pulling fuses or fusible links) will cause other systems in the car to freak out, and on most Infiniti models will also kill your speedometer. The good news is, problems like that are almost always caused by resistance someplace in the wiring, usually bad pin-fits in a connector. By and large dealer techs these days are parts changers paid on flat rate, so they understandably lack the patience to check that kind of stuff unless the DTS shows up and gets them paid. But it's definitely something you can DIY with some patience of your own and a short length of 0.025" music wire. In most cases (although it isn't "by the book") you can fix a bad fit without replacing the female receptacle by bending the male pin 10~15 degrees off perpendicular to increase the contact pressure.

[mikedamageinc]

Thanks for the info. Any tips since I don't have any codes? ABS scanned and no codes. I assume the ebcm main plug is the first to check pins

[VStar650CL]

Yep, and the power connections. Actually, the first thing to check is probably the ABS ground. On Nissan products the ABS always has its own ground lug not shared with anything else, and a bad connection could "sleep" the ABS during malfunctions and result in no codes.

[VStar650CL]

See page PG-43 here. The ABS ground is E43, it looks to be on or behind the lefthand strut tower:
https://www.nicoclub.com/service-manual ... 2%2FPG.pdf

[mikedamageinc]

Thanks for the info VStar, I cleaned up the ground real well and so far no sinking pedal after a few weeks of driving where it was happening daily before. The brakes are still acting weird though. Now they dont always have the same stopping power for the same pedal pressure. It seems to take longer to stop sometimes then other times they grab better. It seems heat related as the longer stopping distances are usually earlier in the drive but I cant swear to it. Even then I can stand on it and they have no problem stopping, just not as well as it should, and then other times it grabs hard.

The best i can assume is from the previous issue maybe the pads are glazed over and lost their bedding and need to be redone. I plan on trying that this weekend and if no change I also snagged a ABS block from the junkyard just in case.

For added info mine is a 2012 M37x, Akebono ceramic pads, Raybestos high carbon rotors (both of which i've run on other vehicles and no problems)

[emm3seven]

Just throwing out an idea here, but when did you last flush your brake fluid? Soft/inconsistent pedal that varies with heat could be waterlogged fluid.

[VStar650CL]

Thanks for the info VStar, I cleaned up the ground real well and so far no sinking pedal after a few weeks of driving where it was happening daily before.

It never ceases to amaze me how many "insane" problems are caused by crappy ground contacts. We even see it on new cars, Nissan just lets the robots run in the screws and occasionally the paint doesn't break. If they programmed the robots to run down, back a turn, then down again, none of it would ever happen.

The brakes are still acting weird though. Now they dont always have the same stopping power for the same pedal pressure. It seems to take longer to stop sometimes then other times they grab better. It seems heat related as the longer stopping distances are usually earlier in the drive but I cant swear to it. Even then I can stand on it and they have no problem stopping, just not as well as it should, and then other times it grabs hard.

The best i can assume is from the previous issue maybe the pads are glazed over and lost their bedding and need to be redone. I plan on trying that this weekend and if no change I also snagged a ABS block from the junkyard just in case.

For added info mine is a 2012 M37x, Akebono ceramic pads, Raybestos high carbon rotors (both of which i've run on other vehicles and no problems)

That sounds more like a booster issue than pads. When the brakes seem weak, is the pedal high and relatively hard? If so, you may have a sticky check valve. @emm3seven could be right too, moisture in the fluid can cause all sorts of erratic behavior.

[mikedamageinc]

That sounds more like a booster issue than pads. When the brakes seem weak, is the pedal high and relatively hard? If so, you may have a sticky check valve. @emm3seven could be right too, moisture in the fluid can cause all sorts of erratic behavior.

Pedal pressure/feel is exactly the same, the difference is in the stopping power.

Fluid is brand new, i even took off the master to bench bleed to be sure, bled the whole system, drove for a bit slamming brakes on dirt to activate ABS multiple times, bled again and this is where I am, good pedal feel but stopping power is what is inconsistent.

[mikedamageinc]

Just to close the loop on this, I sanded the rotors and pads, re-bedded and all is well now. I also noticed the grease went dry on some of the pad sliding surface which probably contributed to the pedal feel, but I'm sure it was the bedding that was the main issue after the ground was sorted. So back to the original pedal sinking feeling, check the body ground near the abs module and clean it up real well and put a little dielectric grease even if it doesn't look bad.

Thanks again Vstar!!

[VStar650CL]