Sporadic Low Brake Pedal Issue

[mikebw22]

My car goes to the dealer on wednesday. I will be talking with the field rep. about the brake problem before they do testing or swap parts. They will also check out the brake booster which was replaced but does not hold vacuum right after the car is shut off. And yes the check valve is good. Also the drivers outside door button is intermittently working. No doubt a bad door module.
I will continue to update the results.
The service manager and adviser have been very nice and very helpful for all our issues.

Mike

 

[Calvin]

Mike....can't wait to hear what they say....especially when you mention the door button. When the "electrical gremlins" hit my Geny, that was one of the problems! Worked in the morning stopped in the afternoon back to not working in the evening. The electrical reboot seemed to cure that for now. Today I thought I detected the brakes getting soft but it only seemed to happen for just a second....could have been me being over observant. I'm planning a short trip later this week and will keep track of these issues and keep everyone updated.

 

[Type4.6]

Got my car back. Brakes are fixed. They replace the ABS assembly. I'll take a picture of the receipt and post it. My car running well. Just making the Knocking/Clicking noise but dealer say they don't hear anything. I posted a video in another post.

 

[mikebw22]

Mike....can't wait to hear what they say....especially when you mention the door button. When the "electrical gremlins" hit my Geny, that was one of the problems! Worked in the morning stopped in the afternoon back to not working in the evening. The electrical reboot seemed to cure that for now. Today I thought I detected the brakes getting soft but it only seemed to happen for just a second....could have been me being over observant. I'm planning a short trip later this week and will keep track of these issues and keep everyone updated.

The door lock/unlock problem is a very common problem they said. It's an intermittent problem and will get worse. Will either be the outside door handle button or door module. There are 3 modules for the remote key. One in each door and 1 in behind the dash that sends info to a computer.

Actually my brake appointment is on wednesday the 22nd.

Mike

 

[Calvin]

Just a quick update....the soft brake pedel is back but this time it showed up with a rough engine acceleration and sporadic RPM jumps of 1 to 2 hundred almost as if the ESC part of the ABS was engageing or trying to engage.....still no lights...ABS or ESC. Also noticing that right after it does this there is black soot on the exhaust tips that usually only shows up if I take the car on the interstate and blow it out. I'm going to try a "hard reboot" (disconnect battery) today one more time to see if things reset but I think that I will probably need a new ABS unit to fix this once and for all.

 

[mikebw22]

Calvin, Sounds like you have 2 separate problems. Your brake problem and an engine running problem. Engine missfire caused by spark plug usually, injector or coil on plug.
If you did have any misfiring should be a code in the computer for that cylinder.
Might also be a TSB on pcm software update.
Reboot won't fix that problem.

Mike

 

[nyjetfan]

I have a low brake pedal issue that started yesterday. My problem can be reproduced easily. When I step on the brake it slowly goes all the way to the floor. This happens while driving or in park. I'm taking it to the dealer this week.

 

[Calvin]

Thanks for the update Mike!

The rough idle and acceleration has subsided with a new tank of gas....just wondering if I got some of the fall gas blend with extra ethanol or maybe some water (could be old ethanol).
How long did it take for the dealer to change out your ABS unit? Is everything working normal again? I wonder since this is becoming an issue with more and more Gennies.....do you think we are getting "reconditioned units?

Calvin

 

[mikebw22]

Actually taking the car to the dealer Thursday AM. Have been waiting for the field engineers schedule to work out for him to look at our car. The dealer said they already ordered a new ABS hydraulic module. We don't like having to wait this long but that's how it is working out.
The original units are not reconditioned units. It is not common for ABS modules to have problems at least until this particular problem. The replacements should be new also.
I'll post an updat when it's done.

Mike

 

[Type4.6]

Did the pics help Mike? My car took about a week to get everything Fixed.

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[Potty_Pants]

Same thing happed to me with my grand am gt . Had about 8k miles and pedal went to floor almost smashed through a wooden toll booth arm. The service dept knew within hours or one day it was a faulty abs solenoid.

Shame we dont have manual parking brakes..

Ppp

 

[nyjetfan]

Master was cylinder replaced today under warranty and the pedal fade problem has gone away, but the braking has gotten worse. The braking is gradual no matter how hard I press the brakes. I cannot hard brake. Also, after 20 miles of driving the check engine light came on. Bringing it back tomorrow.

 

[mikec]

Master was cylinder replaced today under warranty and the pedal fade problem has gone away, but the braking has gotten worse. The braking is gradual no matter how hard I press the brakes. I cannot hard brake. Also, after 20 miles of driving the check engine light came on. Bringing it back tomorrow.

Does the brake pedal feel hard to push? I'll bet they screwed up the vacuum hose going from the engine to the brake power booster. If that's the case, you have no power assist to the brakes - and I wouldn't drive the vehicle in this condition. Make them send a flatbed. You can test the booster yourself very easily:
1: engine off, transmission in Park, parking brake set normally.
2: start the engine and let it idle for a few seconds to a minute. Doesn't need to be long - just enough to reach a smooth/steady idle. Turn the engine back off.
3: push on the brake pedal slowly until it's pretty firm - taking a good bit of force. Note how far it moved.
4: let the pedal up.
5: push on it again until it feels about as firm as step 2. Hold it there... did it move less than step 3? If so, good. If not... odds are the booster isn't doing it's job.
6: release it again.
7: repeat steps 5 & 6 a few times. Each time the pedal should move less before the force gets high.... each time you push the pedal you are using up some of the "trapped" engine vacuum in the booster so the booster provides less and less assist. Eventually it'll stop helping you completely - after 2 to 5 applications of the brake pedal typically.
8: push the pedal down and hold it with a fair bit of force.
9: while holding the pedal down, start the engine again. The brake pedal should sink quite a bit towards the floor once the engine starts: with the engine providing vacuum again, the booster starts functioning again.

Steps 7 and 9 are the main things to observe; if either doesn't seem to match your car I'd NOT drive the car and make the dealer flatbed it. They screwed up the power braking assist.

The vacuum hose that I'm theorizing about is easy to eyeball: open open the hood and look in the back/right corner (as you face the engine bay from in front of the car). You'll see a white plastic reservoir tank, below this is the brake master cylinder - a silver metal thing. It bolts to a big round black piece - that's the power booster. There should be a fairly large rubber hose plugged into the front of the booster; this hose eventually plugs into the engine to collect engine vacuum. See if the hose looks like it's connected to the booster. Oh, if this hose is leaking it'll affect some of the engine's air-fuel calculations enough to trigger the check-engine light.

There is also a free play adjustment in the brake pedal and in the metal rod/pins between the pedal, booster, and master cylinder. If they didn't make this adjustment, the brake pedal will travel down more than usual before you get any braking action... and the pedal will bottom out against the carpet before fully applying the brakes. This too is an installation error on their part... and another reason to not drive the car and have them flatbed it. If this is your problem, your car will pass the booster test I described and that vacuum hose will be properly installed.

mike c.

 

[nyjetfan]

Thanks for the advice Mike, but I did't see your post until after returning the car. I did drive it back and no it wasn't fun. They've had the car since yesterday with no call back yet. I'll update when I get the car back.

 

[mikebw22]

Finally got the ABS hydraulic module replaced which fixed the brake problem.
They originally replaced the brake booster which ended up not working correctly and so had to replace that again also. Had some other things fixed too but the main problem was getting the brakes working right.
Thanks type4.6 for your info help.

Mike

 

[nyjetfan]

Going to pick up my car tonight. The dealer said they replaced the brake booster and a vacuum hose to get it right. I hope it's right.

 

[nyjetfan]

Picked up the car tonight after the mechanic replaced the brake booster and vacuum hose to the brake booster. I drove out, stopped at the first traffic light and while waiting at the light my brake pedal slowly went down to the floor. I have to bring it back for a third time.

 

[mikebw22]

You probably have the same brake issue that I and others have had. A bad ABS hydraulic brake module. Dealers don't want to replace them right away because of how much they cost. Almost $3K. That's why they wanted to send a field rep. out to check my car. The dealer tried different repairs and said they couldn't do anything else. So I had to diagnose it myself and tell them what it was.
Anyway you probably have a bad solenoid in the ABS module that's allowing the brake fluid to leak internally. Since it is a brake issue they should get that resolved right away.

LMK if you need any more information.

Mike

 

[nyjetfan]

"The dealer tried different repairs and said they couldn't do anything else". This has been my experience with the dealer also on the brake issue and 2 other issues. The dealer acknowledged the car has problems but said they checked everything, but don't know what's wrong and then sent me away. The Genesis is too much car for the service department at these Hyundai dealers and this will deter a lot of people from buying them. My problems aren't big ones, but the dealerships I went to cannot fix them. I can't imagine Infiniti or Lexus or BMW sending customers away with a known problem telling them there's nothing else they could do.
My wife and I went to dinner with another couple and I drove us all in the Genesis. My friend was in the back seat and was blown away by the interior and ride and couldn't believe it was a Hyundai. He has an E350 and has been driving Mercedes E class for 15 years. He was very impressed. I was glad he didn't ask me what I thought of it, 'cause I would have had to tell him about the problems getting it serviced correctly. It's such a shame because the car is as my friend said "Really nice."

 

[Keith1947]

I am very happy to find this forum and thread because I have had two recent incidents of my brake pedal going almost to the floor. I have a 2009 Genesis 4.6l with approx. 90k miles.

After the first incident about three weeks ago the Hyundai dealer in San Jose Ca replaced the front brakes and changed the brake fluid at a cost of about $700. Yesterday the brake pedal again went almost to the floor while stopping on a city street. I almost rear ended the car ahead of me. The only way I can describe the problem is the brakes are good and then they are bad on the next application. No warning lights, no gradual deterioration, just instant very poor brakes. Pumping improves the brakes slightly but they rapidly faded when held. They car is at the dealer again and the shop forman has told me he will replace the master cylinder, cost about $650 -$750.

After reading this forum I am nervous that I am just hanging new parts on the car and hoping that it fixes the problem.

Even worse, like others have mentioned, it has totally destroyed my confidence in the mechanical soundness of the car. With tremendous freeway traffic here in the SF Bay area and the rapid stopping you need to do with traffic jams, brakes are somewhat important. I wanted to keep the car for another few years but now I think I need to fix it and look for another automobile.

Can anyone tell me if this problem is just part of the high tech cars with 4 wheel disc brakes, power assist, abs etc or is this just poor engineering in the Hyundai Genesis?