Soft/Spongy/Fading Brake Pedal - Bad ABS Module? - Kia Forum

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post #1 of 17 (permalink) Old 09-23-2018, 01:15 AM Thread Starter
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Soft/Spongy/Fading Brake Pedal - Bad ABS Module?

My wife drives our 2007 Entourage SE that current has 90,000 miles on it. A short time ago the brake pedal got “soft” or what some people might call “spongy” accompanied with gradual “leak down” of the brake pedal. As this is normally a symptom of a failing master cylinder, I replaced the master cylinder. This did not improve the situation. Next, I replaced the rear brake pads (although they were probably only half worn) to push more fluid back into the reservoir in hopes it would “tighten up” the pedal feel. This also did not improve the situation. The front brake pads are relatively recent and not in need of replacement.

As I did everything I knew to do that might resolve this problem and could not, my next step was to take the van into the dealership and have them diagnose what was going on. The dealership indicated that what I’m experiencing is a failure of the ABS system that they don’t see very often. They also indicated that part costs alone would be $2500 dollars. Although they did not specifically indicate which part(s) they were talking about I’m assuming that they mean the ABS module itself which is a Kia/Hyundai part that isn’t available from aftermarket suppliers. I’ve heard that even salvage yard parts would need to be “flashed” or “interfaced” with the vehicles control systems in order to work properly.

Has anyone experienced the type of symptoms I’m describing and was it indeed the ABS module that was the cause? How did you repair your vehicle? Is there a way to fix this problem without a 4-digit price tag?

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post #2 of 17 (permalink) Old 09-25-2018, 12:10 PM
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I replaced all brake pads/rotors/fluid and the pedal was still a bit mushy. I then took the Van on a wet road going 50mph and stomped on the brakes several times to engage ABS. Pedal is as firm as ever afterwards. This has worked for me and others. Worth a try just pick a safe location on wet pavement or gravel. I would junk the Van if any repair costs $1500 and up as the market value for them is so low. The dealership indicated they do not see this problem very often. It's a good sign for you as an owner and a tell-tale sign that they are throwing parts to solve the issue. In this case, it's an expensive part.

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post #3 of 17 (permalink) Old 09-25-2018, 01:01 PM Thread Starter
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Thanks kia-nynj. What you suggest is certainly worth a try and doesn't cost anything. Of course, it was raining here in Fort Worth all weekend and everything was wet. Now, the streets are dry. Maybe I can find someplace with lots of puddles.
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post #4 of 17 (permalink) Old 09-25-2018, 03:19 PM
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The ABS unit on a 2007 KIA/Hyundai does not need to be "married" or programmed... Later models and some other makes (Chrysler products) do need to be "matched/programmed" ...

I bought an Ancel AD610 reset scanner to bleed my 2006 Jeep Liberty brakes for $109.00 on ebay and have since used it often to reset un-resetable codes... Cheaper than visiting a dealer just once...

BadDog42 the symptoms of soft pedal and slowly falling pedal sounds like air in the ABS unit... My Jeep was that way and the custom bleeding gave me a firm pedal...

I look at the purchase as just another tool I can use in the future (and have)...
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post #5 of 17 (permalink) Old 09-25-2018, 04:40 PM Thread Starter
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DavesSpectra - Thanks for the useful information. I'm glad to hear that if I had to go to a salvage yard replacement ABS Module it would not have to be "married/interfaced" to the cars electronics. However, I don't know if the Ancel AD610 scan tool you mention would help me as the ABS malfunction indicator in the instrument cluster is not illuminated. Thus, I don't know that there are any trouble codes in the system at all.
You also mentioned that you used the scan tool to bleed your Jeep's brakes. I'm at a loss to understand how the scanner could help with a bleeding. Does it have some mode where it cycles the valves in the system or somehow pressurizes the lines to aid in bleeding? You use the term "custom bleeding" and that intrigues me. How did you actually go about doing this? The bleeding process I'm familar with is the "old school" one person at the pedal, one person at the wheel method.
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post #6 of 17 (permalink) Old 09-25-2018, 05:08 PM
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Pretty sure he was meaning that YES it has a mode that activates the ABS motor which will push trapped air out of the ABS section and into the lines for bleeding. Dog gone new fangled technology these days to bleed brakes of ABS equipped vehicles. OLD School will work...IF you don't run the res. empty or push air into the abs assy when doing something like a MC change. But I'm sure DavesSpectra will show up again to confirm.
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post #7 of 17 (permalink) Old 09-25-2018, 05:51 PM
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I took my Van for another spin an hour ago. My brakes now function/feel like a sports car, no kidding. I have had the Van for more than 2 years with spongy pedal (bought used). It was scary when driving fast or when I was closely behind someone. Not anymore!
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post #8 of 17 (permalink) Old 11-12-2018, 02:26 PM Thread Starter
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OK folks, here's what I've done todate: 1. Replaced Master Cylinder 2. Replaced ABS Module (pump and control unit) 3. Bled brakes manually once and electonically via scan tool twice, and still have a mushy/fading brake pedal with no ABS, EBD (Electronic Brakeforce Distribution) or ETC (Electronic Traction Control) trouble codes. In fact there are no trouble codes at all. I'm at my wits end on this as the van appears unrepairable which is not only my opinion but also that of the shop that the van's been at for the past week. So, if anyone has any ideas of what could be causing this, please let me know.

Oh, before the ABS module replacement but after the master cylinder replacement, I did take the van out in the rain twice and exercised the heck out of the ABS before a manual bleed which some have mentioned fixed their problems. It didn't do anything for me.
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post #9 of 17 (permalink) Old 11-17-2018, 01:11 AM Thread Starter
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As an addendum to the post above:

After doing all that I previously described, I figured that the only other thing that could cause a "disappearing" brake pedal had to be the vacuum booster. Well, today I replaced that and guess what - NO DIFFERENCE in brake operation. I still have a "mushy/spongy/disappearing" brake pedal that is really dangerous to drive with. Also be aware that when I replaced the vacuum booster I checked the vacuum supply hose and check valve and they are working as they should.

So, I've now done everything that I, the Kia dealership that said my problem was with the ABS module and the independent shop that replaced the ABS module and kept the van for 2 weeks trying everything they thought of that might work, know to do. FYI - the independent shop had a scan tool that could read all the brake system parameters and could "auto bleed" the system. What it appears we've all come to realize is the van is basically "unrepairable" by mere mortals. Perhaps a Kia/Hundai vehicle braking system designer with all the time in the world, following the 143 pages of brake system diagnostics present in the 2006-2007 service manual might stumble on a solution but I don't know anyone like that. I suspect that the problem lies somewhere in one of several electronics modules but with no trouble codes triggered, how would a person know which one? What I'm experiencing with this Hyundai is unlike anything I've ever come across with the mostly domestic makes I've owned over the years.

Thus, I've come to the realization that I'm going to have to donate this vehicle to a charity for the tax writeoff with full disclose that I would not recommend it be driven in it's current condition. It's a real shame as the vehicle inside and out looks great and only has 95,000 miles on it. We've owned it for 10 years after purchasing it in 2008 with 8,500 miles and has up until recently been my wife's daily driver.

Realize, I'm not a novice when it comes to vehicles. We have a 1971 Buick Centurion convertible I've maintained for the past 43 years since it's purchase in 1975. I also maintain my wife's one-owner 1980 Datsun 280-ZX. Without ABS or Electronic Stability Control (and fuel injection in the case of the Buick) these vehicles are easy to keep operational.

I'll never purchase another Korean manufacturer vehicle again.
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post #10 of 17 (permalink) Old 11-17-2018, 03:55 AM
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It sounds like you still have air in the brake system and it is sitting at a high point in the lines, in the ABS module, or in a calliper slave...
I have a 1997 Ford Ranger that I replaced the slave throwout ass'y and couldn't get it to bleed within the car and found that the whole "system" (master clutch cylinder/clutch line/and slave cylinder (with throwout bearing) had to be removed/reassembled/hung up high (per the service manual) and pumped/bled in this configuration and reinstalled after this manoeuvre...This finally solved my soft clutch problem....

The Jeep Liberty (2006) had run dry (air in the system) and air got trapped in both the lines and the ABS module... The line going to the back has a high spot like an inverted "V" that had air at the top that wouldn't easily come out of the system... I ended up forcing a lot of fluid through the line (power bleed) then ran the ABS bleed software and I FINALLY had a firm pedal.... The Jeep never threw any codes with air in the system... and the Ranger had no "monitoring" on the clutch lines... The Jeep does slowly go down a little on the pedal but that is after the car has stopped and the brakes are firm... I attribute this to the soft design by Chrysler that does stop the jeep...

You need to find a true brake specialist as a regular mechanic or dealer service dept can't locate where the problem is...

As far as KIA's or Hyundai's are concerned ...it's not the car but the failed repair attempts that has got you going... ABS systems can be a real pain and require knowledge to get them to work properly... and this is on ALL brands of cars...
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