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Brake Actuator clicking when I enter vehicle

86K views 176 replies 61 participants last post by  Scott K.  
#1 ·
Hey,

So I recently noticed that my car was making a clicking sound when I opened the doors. No, it's not the lock. It's not the shift lockout. It makes a series of clicks up under the dash. When I first noticed it, I posted a video where you could hear it and a helpful poster (on FB) thought it might be one of the three HVAC actuators. For the record, it might click 5-6 times, but sometimes it goes 20-30 before stopping.

I took it over to my local dealer and they told me it was actually the 'brake actuator'. When describing the symptoms to them originally, I had only noticed that morning that the clicks always stopped when you put your foot on the brake. The service guy told me that GM was aware of the issue with the brake actuator and no solution was yet available. According to the service guy, this is harmless. I never consider an issue with the brakes 'harmless'. If the actuator is rotating needlessly or whatever it controls is slamming against the stops repeatedly, this will eventually lead to a failure of some sort -- again, this is the ABS brake system so is that failure catastrophic?

Does anyone else notice a clicking sound in or under the dash when you enter your Bolt (even from passenger side, or rear hatch, with key fob)? Did GM diagnose your issue? Did they provide a solution? The service guy mentioned a bulletin on it but did not give me a number or other identifying information so I could track it. So I don't really have a way to track GM's progress on a solution.

Anyone else have a Bolt that talks to them when they open the doors or hatch? Thanks in advance
 
#2 ·
Hey,

I took it over to my local dealer and they told me it was actually the 'brake actuator'.
It is the Bosch i-Boost power assist unit for the brakes. There is a tooth broken out of the gear rack on the side of the master cylinder unit. I don't know how unsafe it is, but it is broken and should be replaced under warranty. Your dealer is incompetent. Call GM!
 
#14 ·
It is the Bosch i-Boost power assist unit for the brakes. There is a tooth broken out of the gear rack on the side of the master cylinder unit. I don't know how unsafe it is, but it is broken and should be replaced
Hi Gjetson,
how do you know it is a tooth broken?
Have you seen it broken?
Maybe you could share the picture of it broken if available?
From what I found it seems not too big deal to change the gear. Am I right? If yes maybe you could advice on where to get the spare parts for the booster?

I have exactly the same problem with the same symptoms on my 2016 Volt which is out of the warranty. It started to make this noise recently, brakes work as supposed to, just the noise is annoying.
 
#5 ·
#6 ·
Yeah, I found it. It has a helpful sticker that reads iBooster with several multi-digit numbers. I read Bosch's information on it and realized that it played a bigger role in the operation of my vehicle. The Bosch material says that it pressurizes the hydraulic system and helps balance the regenerative and friction braking of the vehicle. This is an interesting point.. Several weeks ago, I noticed a drop in the aggressiveness of my regenerative braking system such that I was using the paddle more. When you learn the deceleration curve of the vehicle and then you have to relearn it because it changed.. very strange. The video seems to support the written information I have.. that this iBooster actually participates in both regenerative and friction braking.

Rather than poke around with the mooks at my local dealer, I dropped a dime to GM Customer Care and explained the situation. If I die in a fiery crash now, there are records at both the dealership and national level about my concerns with the safety of the vehicle.

Who knows.. maybe I am going a little crazy listening to that clicking and the braking is working just fine. But if I am right, and it results in any damage, GM will be holding the bag (assuming I survive)
 
#26 ·
Would there be any way you could email me a copy of your service bill? My Bolt is doing the same thing. Last time when I had the rear axle problem, I showed them a Bolt forums service record and they immediately repaired the problem. They thanked me profusely for bringing the other person's service info. My Bolt seems to get every problem, sadly.
 
#10 ·
Thanks for the helpful thread. There are more reports of the same issue at insideevsforum.com. It may be a more widespread issue than GM or others realize, so I thought it might be helpful for me to report I have this identical problem. Perhaps it is worth a recall, or at least a service bulletin?

Also would appreciate any dealer recommendations in Northern California. Not sure I'm getting the best service possible from mine.
 
#11 ·
Hey Bill,

I emailed you a link to a pair of video clips that you should be able to review and share with them. As far as I know (I'm just a consumer), there is no public TSB or recall on this yet but I personally have read or otherwise communicated with at least 5-6 Bolt owners that have or are experiencing the same thing. In my case, they replaced the iBooster (actually the master cylinder assembly and brake pedal assembly) and I think they might have done a small software update. It works great now, so I'm happy.

In the bigger picture, I think I am a typical Bolt owner with a 2017 (late August) that has 16000 miles on it. I drive mostly in L, use brakes infrequently, and do 70/30 surface vs highway driving. I probably press the brake pedal a few times a day but no more than two or three per drive in normal operation. So I don't think I did anything to precipitate this. I also wonder if more owners are living with it as a 'normal' thing since the first dealer I took it to told me 'no error codes, that sound is perfectly normal'.

Anyway, good luck getting the repair. That part is hard to get and took about 6 weeks to arrive.. and only two hours to install.

Mike
 
#12 ·
2017 Chevy Volt has same problem, repeatedly

I live on Kona side of Big Island. Dealer is 2 hour drive down mountain to Hilo side, each way. I have had the entire brake assembly replaced twice, but noise keeps returning. GM Customer Care is awful (they seem clueless on anything technical), as is Dealer. The only mechanic certified on Chevy electric vehicles (who has done the first 2 replacements told me he replaces brake assembly often on both Bolts and Gen 2 Volts for this reason, yet GM Customer Care claims they have no other alerts on Regen Braking assembly). The actuator makes this clicking noise once you activate electronics in car (open door, use FOB). It is loud and lasts until you start using brake pedal. If brakes are hot, the actuator won't make clicking noise. That means I must wait a couple hours before proving to Dealer that the problem has returned, whihc forces me to stay overnight in Hilo.

I had to drive it over again and rent hotel, as Gm insisted. Now, I will return later thsi month to try my third repalcment of brake assembly. I have run up large hotel bills on several trips to get this fixed. Given the history, I dont think GM will be able to fix it. No one would ever buy my car when I explain to them that the nosie is do to design defect in brake assembly that appears to not be amenable to repair. Has anyone filed a lemon claim because of this problem.

PS: I wont let my wife drive car because we live on side of volcano, with heavy need for brakes. She is not a great driver and would freak out if brakes failed on the mountain. As result, we have driven the car very little. I have bought many GM cars. I am really impressed by the Volt technology. But, this brake problem is serious and GM cant seem to fix it, as actuator noise returns within 2 months of replacing the entire assembly. Has anyone else had success with installing a new assembly? Very unhappy with this car
 
#72 ·
2017 Chevy Volt has same problem, repeatedly

I live on Kona side of Big Island. Dealer is 2 hour drive down mountain to Hilo side, each way. I have had the entire brake assembly replaced twice, but noise keeps returning. GM Customer Care is awful (they seem clueless on anything technical), as is Dealer. The only mechanic certified on Chevy electric vehicles (who has done the first 2 replacements told me he replaces brake assembly often on both Bolts and Gen 2 Volts for this reason, yet GM Customer Care claims they have no other alerts on Regen Braking assembly). The actuator makes this clicking noise once you activate electronics in car (open door, use FOB). It is loud and lasts until you start using brake pedal. If brakes are hot, the actuator won't make clicking noise. That means I must wait a couple hours before proving to Dealer that the problem has returned, whihc forces me to stay overnight in Hilo.

I had to drive it over again and rent hotel, as Gm insisted. Now, I will return later thsi month to try my third repalcment of brake assembly. I have run up large hotel bills on several trips to get this fixed. Given the history, I dont think GM will be able to fix it. No one would ever buy my car when I explain to them that the nosie is do to design defect in brake assembly that appears to not be amenable to repair. Has anyone filed a lemon claim because of this problem.

PS: I wont let my wife drive car because we live on side of volcano, with heavy need for brakes. She is not a great driver and would freak out if brakes failed on the mountain. As result, we have driven the car very little. I have bought many GM cars. I am really impressed by the Volt technology. But, this brake problem is serious and GM cant seem to fix it, as actuator noise returns within 2 months of replacing the entire assembly. Has anyone else had success with installing a new assembly? Very unhappy with this car
I am experiencing this on my 17 Bolt now and I live in Hawi. Headed to Hilo next week to get it looked at. any advice?
Thanks,J-man
 
#13 ·
The electric power brake booster is made by Bosch. GM doesn't make them. They are dependent on their supplier

As for worrying about coming down the mountains with a failing brake booster, the hydraulic brakes on this car will work without boost, just requiring greater pedal pressure. But, in fact, this is the safest car you can buy for driving in the mountains.
You should be driving in L, and using the paddle. This is a totally separate system from the hydraulic brakes, and allows driving in the most mountainous conditions without ever using the brakes at all, while recouping energy.
 
#16 ·
Yes most probably you are right. However I found some strange facts:
1) in one of the frorum threats Bolt owner had his iBooster replaced twice and the problem came back soon. Then it would mean that both replacements were taken from the same defective batch?
2) the iBooster ticking problem was typical to 2014 Tesla, however at speeds above 25 mph. For some owners their dealers also went with the booster replacement. However in January 2015 Tesla issued a software/firmware update 2.2.115 and the ticking disappeared (the link in here).
3) another Bolt owner told that besides iBooster replacement his dealer did as well some update. Nobody else in the Bolt/Volt forums told that or nobody knew they received an update.

So I do not reject that the clicking/ticking noise from the iBooster is coming due to software/firmware which might be forcing for some reason the stepper motor to continue working AFTER master cylinder piston has returned to its home position thus making the noise. But this is my guess.

If master cylinder piston has not returned to its home position then we could see the brake lights always on. I just experienced and fixed such issue combined with Service Stabilitrak + BRAKE red light + booster temporarily not working at all. I thought I found the issue but now I'm in doubts again. If the iBooster tooth had separated it could stuck in between gears and cause all the problems I had. The booster clicking noise appeared afterwards, it was not there before. Here is the link to the problem and my fix.
 
#17 ·
1) in one of the forum threads Bolt owner had his iBooster replaced twice and the problem came back soon. Then it would mean that both replacements were taken from the same defective batch?
2) the iBooster ticking problem was typical to 2014 Tesla, however at speeds above 25 mph. For some owners their dealers also went with the booster replacement. However in January 2015 Tesla issued a software/firmware update 2.2.115 and the ticking disappeared (the link in here).
3) another Bolt owner told that besides i=Booster replacement his dealer did as well some update. Nobody else in the Bolt/Volt forums told that or nobody knew they received an update.
As for having the same problem twice, there was at least one Bolt owner who had two defective traction battery packs replaced...stuff happens.

The clicking in Bolts appears to happen at rest, rather than while moving, as in the Tesla cases. But if it is a software problem, god help us. GM is not a Silicon Valley tech company. ?
 
#18 ·
Update regarding the assumption on the master cylinder piston not in home position.

I've read the brake booster control unit sensors using GDS2. Both the input and output rods are at exactly "0" position, which means at home position. What theoretically might be causing the problem - the other two parameters.

Brake Pedal Position Calculated from Input Rod Position Sensor 1 which is very very slighly above zero at 0.006in.
Brake Pedal Position Calculated from Input Rod Position Sensor 2 shows 0.0087in.

I succeded to achieve a perfect zero for Brake Pedal Position Calculated from Input Rod Position Sensor 1, but the ticking from the booster still there.

I reached the Chevy dealership and shared with them all the info I have. Will see if they will be able to support my troubleshooting distantly (I'm in Europe).

As well I reached Bosch central office in Germany, they promised to come back to me after their investigation on the potentially failing iBooster. I asked them to look to their records. I hope Chevrolet has reported to Bosch about a number of replacements they've been doing.
 
#21 ·
Just got my 2018 Bolt back from the Chevy dealer warranty repair where they fixed the same clicking sound by replacing the SL-N-Cylinder (04650-C) and its fluid. They also replaced the brake booster control module assembly. My service advisor said the parts would have been over $1200 + labor. He also said the tech found the issue in this forum and not on the Chevy service bulletin website. Thanks to everyone who gave answers to this issue. The dealer also said that Bolt/Volt forums are more active then all of the other Chevy forums.
 
#22 ·
SL-N-Cylinder (04650-C)
Its a master cylinder, right?

They also replaced the brake booster control module assembly
You mean the brake booster control module itself OR you mean the assembly = booster+master cylinder+brake pedal assembly ?

My service advisor said the parts would have been over $1200 + labor
That is why I'm not keen yet to replace it (warranty not valid for my car anymore).

Pharlyn, could you please ask your service advisor:
  • if they consider it as failure which might cause later more serious malfunction of the brakes OR its annoying thing only, I mean the clicking sound?
  • if they could dismantle all the assembly (or at least the iBooster) apart to carefully inspect what exactly has failed?
  • if they are going to discard everything they dismantled maybe they could sell it to me for some symbolic price?
 
#24 ·
Took my 2017 Bolt into the shop today with the brake booster tapping noise. They "DIAGNOSED AND ORDERED BRAKE BOOSTER/MASTERC YLINDER ASSEMBLY AND PUSH ROD RETAINER"

Sadly, the part is on order and may take a few days (weeks?) to arrive due to the GM strike since parts suppliers shut down, too. Happily, it will be a warranty repair.

Thanks to all in the thread for sharing the symptoms and diagnosis.
 
#27 ·
Started noticing this same tapping sound in my Bolt a few weeks ago and my local dealer has just confirmed the source is the brake booster. Unfortunately for me, the warranty covering the brake system is up on this car and dealer quoted $2K to replace the booster assembly. I’m curious if anyone has confirmed if this is truly a safety consideration or not? Or if anyone has this problem and decided to leave it alone and what the outcome was? My understanding is the Bolt’s regenerative braking will continue to function even if the brake booster were to fail since they are separate systems but I think there are still scenarios where friction braking is important. It’s not clear to me from booster documentation how functional the hydraulic brakes would be without the booster working.

I talked with the certified Bolt tech at this dealer and he simply couldn’t tell me if this sound was a sign of impending booster failure or not where the tapping sound was coming from specifically within the assembly. Judging from the video linked earlier in the thread, I’d guess the sound is coming from the input rod sliding up against one or the other limit of the boost body. Doesn’t really give me any insight into why the problem would suddenly appear or if it has long term consequences though. Has anyone managed to learn more about this failure mode?

I’m also curious if anyone else has had this job done not under warranty and if the price I’m being offered is comparable?

Appreciate any information. This thread was tremendously helpful in guiding the service folks to the problem quickly.
 
#30 ·
I have the exact same problem on my 2018. I took it to the dealer and they can hear the problem but told me that it's not an issue with performance of the car and they can't get approval from GM to fix the issue. They said that without approval they can't guarantee they will be reimbursed. Complete BS. I'm going to find a certified Chevy EV dealer that has a mechanic and try my luck there. It's a nonstop clicking even when the car is off. It only stops once the brake is pressed, so I'm confident that it's the exact same issue. I've also noticed that the regen brake is not as effective.
 
#32 · (Edited)
Update after almost a year with this annoying ticking/clicking noise:
1) I ended up by replacing the iBooster two times, both times with a used one. I did everything by myself. If you need advices for the replacement I'll be glad to help you.
2) I disassembled the original iBooster to inspect what was wrong with the internals. Mechanically everything looks in perfect condition, no signs of wear of any of gears. So definitely the attached electronics or the attached position sensor failed. You can change this sensor but to do that anyway to have to remove the full brake booster first to gain access to it.
 
#39 ·
I just started having this exact issue. Constant tapping (I thought it was part of the music at first) that disappears if I hold down the brakes. Happens with the car stopped as well. Guess I'm making a dealer appointment. 25k miles. Reading around, it looks like the typical potential fight with the dealer and then they put an exact same $1200 unit in that will probably fail again out of warranty. Wonderful.
 
#42 ·
FWIW, I have a ’17 Bolt with 21,724 miles on it, 4 1/2 months out of warranty. I was out-of-town for a month and returned two weeks ago and the tap-tap-tap was present for the first time. Thanks to this forum and insideevs.com I’ve traced it to the iBooster, like others. Very disappointing, especially as I’m dubious that GM will cover it. Seems like a pretty common failure, there should be a recall on it. While I’m not the savviest of mechanics, I’m definitely interested in what’s involved in doing it myself, as Mindaugas has done twice.
 
#43 ·
Add me to the growing list of people with this issue. 2017 Bolt with 22,100 miles. I have 2 weeks left on the bumper to bumper warranty. Hopefully, I can get it in and repaired within that time if that's the portion of the warranty that covers it. Just figured I'd pile on so we all realize how pervasive this issue is. Will update with my experience at the dealership.
 
#44 ·
Lucky you with 2 weeks left on the B2B warranty! I’d get it in ASAP. I’m now 5 months out of warranty with 21,920 on mine. Problem presented 5 weeks ago when I returned from a month out of town and the car wasn’t driven that whole time. My unit was made in Poland, says so right on the label. I haven’t had a chance to bring it in, but it’s not going away so I’ll have to. I’m not happy about it, though.

Do let us know, please, about your experience.
 
#47 ·
Same thing happened to me...it would make the noise every time except for when I went to the dealer. The ticking got louder and longer. It started with a few clicks then eventually about two minutes long, even after going into gear. On the third visit for this, the tech heard the sound but said it was normal!
I showed him and the manager videos I took as well as some post and YouTube video showing the issue was in-fact the brake booster. I told them I felt unsafe driving the car and required a loaner until they would fix it. Long story short, they gave me a loaner until the repair was done.
My recommendation is they next time you hear it to bring it in ASAP. I don't remember the exact amount but the work order said it was a $1500 repair. I made it in at 33k miles and it was covered under warranty, if I would have waited longer I would have been on the hook for it.
 
#53 ·
Mine would stop as temps got colder.

Sent from my SM-N975U using Tapatalk
Taking mine in for the second time this morning. Was reliably making the noise yesterday. This morning with temp at 41F, not so much. I’m going to try preconditioning for about 40 minutes to try to coax the malfunction out of its slumber, but I’m also leaving the car at the dealership this time in the event that it doesn’t show up soon. Hard for us as a 1 car family. Thanks for the tip on the temperature issue.