Brake pedal travels far before engaging

Tiny
AONEAL10515
  • MEMBER
  • 2009 CHEVROLET COBALT
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 168,000 MILES
My brake pedal travels little less than halfway before it seems like it engages. Once it engages the brake pedal is hard like a lot of pressure is there. Recently, I have changed the master cylinder, bleed brakes, replaced front end struts. Every time I take it somewhere they said they don’t see anything wrong. I know that when I got the car the brake pedal wasn’t like that. It seems like it takes a lot to stop the car. Some days it feels better than others. It seems to have more of a problem the more I use the brake.

One day I heard this loud pitch medal on medal sound that went away. My mechanic looked at the brakes, calipers, wheel bearings, and rotors. Said everything seemed okay. He couldn’t get the sound to happen again.

The car doesn’t have ABS or traction control. Problem has been there for about two months.
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Tuesday, April 2nd, 2019 AT 9:38 PM

17 Replies

Tiny
JOETECHPRO
  • EXPERT
Hey Aoneal10515,

Has the brake pedal only been like this since you replaced the master cylinder?

Or did you replace the master cylinder because of this fault and it did not make any improvement?

Are you sure the car does not have ABS? From what I can see from the year model you should have ABS. There is a specific bleed procedure to carry out when replacing parts on these systems.

There is a TSB applicable for your vehicle that I have attached below.

Your vehicle may be affected by this and may require a replacement brake pressure modulator valve.

I would advise if you go to a Chevrolet dealer and ask them if this TSB is applicable. They can then identify what you may need and quote you on the work.

You can then decide whether or not to have them do the work, get quotes elsewhere or do the work yourself.

Hope that helps. Let us know how you get on.

Regards, Joe
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Wednesday, April 3rd, 2019 AT 10:36 AM
Tiny
AONEAL10515
  • MEMBER
No, my car does not have ABS. Even the dealership confirmed it and the mechanic. When he replaced the struts he told me I didn t have it.

I replaced the master cylinder because the brake started have long travel. After replacing the master cylinder the brake wouldn t sink in at lights.
When the mechanic inspected it he said it had way too much play. If you pumped the brakes the master cylinder would move erratically. He bleed it multiple times even power bleed it. But it stills feels weird.

Just yesterday, I was travel down a hill, I had to brake abruptly and hard and it felt as though I was on ice but I wasn t.
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Friday, April 5th, 2019 AT 1:12 PM
Tiny
JOETECHPRO
  • EXPERT
Hey Aoneal10515,

Can you please get the TSB check done from my previous message with the brake pressure modulator valve and let me know if that helps.

It looks like this is a known issue that a dealer will be able to carry out for you relatively cheaply and will hopefully fix the issue.

Regards, Joe
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Friday, April 5th, 2019 AT 6:22 PM
Tiny
AONEAL10515
  • MEMBER
Chevrolet dealership said this TSB did not apply to my car. I replaced front brake calibers today because I felt one sticking. The issue still is there. Is it possible that it is the Brake Pedal Position Sensor?
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Sunday, April 14th, 2019 AT 5:34 PM
Tiny
JOETECHPRO
  • EXPERT
Hey Aoneal10515,

Did you have any parts replaced before this issue started happening?

Like you said if the issue did not use do be there can you trace any brake repairs before this fault started?

Some bad brake linings could cause problems, aftermarket brake pads/shoes are a cause of many issues.

If it seems to get worse the more you use the brakes then I would say it is potentially to do with the fluid or will be an issue at one/more of the wheels where the brakes get hot.

You have carried out a full brake fluid flush? Old fluid can hold moisture and cause a spongy pedal that gets worse as the moisture boils.

You have drum brakes on the rear of this vehicle?

Regards, Joe
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Tuesday, April 16th, 2019 AT 6:09 PM
Tiny
AONEAL10515
  • MEMBER
The only part I installed before the brake master cylinder was a thermostat.
I had Wagner pads installed.
After, the brake calipers were done the brake pedal felt worst. Before installing the calipers; I could be fully stopped and fit my other foot under the brake pedal. Now, I can t.
After the calipers were replaced, it doesn t get worse the longer I use them.
But now the pedal is going further than before.
All the brake fluid was flushed when I had the master cylinder done. I have drum brakes. Attached is a recent picture of them from Sunday when I had the calibers replaced.
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Tuesday, April 16th, 2019 AT 10:10 PM
Tiny
AONEAL10515
  • MEMBER
Here s the other side of them.
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Tuesday, April 16th, 2019 AT 10:11 PM
Tiny
JIS001
  • EXPERT
According to your vehicle specs you do have ABS. If you have a brake pedal position sensor then definitely you have ABS. Here is what is listed for your brake system unless you want to provide a VIN number to cross reference. Here is what your braking system has.

Collision

Search vehicle information
46
2009 Chevrolet Cobalt L4-2.2L
Components
Vehicle Brakes and Traction Control Antilock Brakes / Traction Control Systems Description and Operation Components
COMPONENTS
ABS Description and Operation

This vehicle is equipped with the MK 25 E Continental Teves antilock braking system.

The vehicle is equipped with the following braking systems:

* Antilock Brake System (ABS)
* Engine Drag Control (EDC)
* Electronic Brake Distribution (EBC)
* Hydraulic Brake Booster
* Traction Control System (TCS)
* Vehicle Stability Enhancement System (VSES) (w/JL4)

The following components are involved in the operation of the above systems:

* Electronic Brake Control Module (EBCM)-The EBCM controls the system functions and detects failures.
The EBCM contains the following components:
* Brake Pressure Modulator Valve (BPMV)-The BPMV contains the hydraulic valves and pump motor that are controlled electrically by the EBCM. The BPMV uses a 4 circuit configuration with a diagonal split. The BPMV directs fluid from the reservoir of the master cylinder to the left front and right rear wheels and fluid from the other reservoir to the right front and left rear wheels. The diagonal circuits are hydraulically isolated so that a leak or malfunction in one circuit will allow continued braking ability on the other.
Important: There is a rubber isolator located under the BPMV and on the mounting studs. The rubber isolators protect the BPMV and the EBCM from vehicle vibrations.

The BPMV contains the following components:

- Pump Motor
- Inlet Valves (one per wheel)
- Outlet Valves (one per wheel)
- Master Cylinder Isolation Valves (one per drive wheel)

* The wheel speed sensor receives a 12-volt power supply voltage from the electronic brake control module (EBCM) and provides an output signal to the EBCM. As the wheel spins, the wheel speed sensor sends the EBCM a DC square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.
* Traction Control Switch-The TCS is manually disabled or enabled using the traction control switch.
* Brake Pedal Position-The EBCM uses the BPP sensor as an indication that the brake pedal is applied.
* Lateral Accelerometer Sensor (w/JL4)-The EBCM uses the lateral accelerometer sensor as an indication of the lateral acceleration of the vehicle.
* Yaw Rate Sensor (w/JL4)-The EBCM uses the yaw rate sensor as an indication of the yaw rate of the vehicle.
* Steering Wheel Position Sensor (SWPS) (w/JL4)-The EBCM uses the SWPS as an indication of the position and rotation of the steering wheel.

I have seen where after a pad replacement the actuator go bad. You may want to try a bleed but you would need an advance scan tool to bleed the ABS unit. And again, if you do not think you have ABS, we need the VIN number to cross reference and see why you do not have ABS?
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Thursday, April 18th, 2019 AT 12:22 AM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
I would like to see a video of that master cylinder move erratically when you press the brake pedal.
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Thursday, April 18th, 2019 AT 3:53 AM
Tiny
AONEAL10515
  • MEMBER
Hello,
Here is the vin number: 1g1at18h997202571.
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Sunday, April 21st, 2019 AT 2:54 PM
Tiny
KEN
  • ADMIN
If I can jump in here, it looks like the rear shoes are worn out causing the low pedal. here is a video of the job being done on a similar car which shows how to adjust the new shoes once you have replaced them:

https://youtu.be/1j7qDoi1LP0

Please run down this guide and report back.
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Wednesday, April 24th, 2019 AT 12:33 PM
Tiny
AONEAL10515
  • MEMBER
Hello,

I replaced the shoes today and the brake pedal is still spongy.

So far, I ve replaced brake master cylinder, brake calipers, brake pads, and brake shoes. My pedal still hasn t changed. I don t know where else I go from here. No leaks still. The car has the appropriate amount of brake fluid.

Thank you
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Wednesday, April 24th, 2019 AT 7:26 PM
Tiny
KEN
  • ADMIN
Lets use three sets of vise grips and gently close off the rubber flex hoses. this should tell us if the problem is at the master or the wheels. Did you bench bleed the master if not this will be the problem? here is a guided that tells you how to bleed it correctly:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Please run down this guide and report back.
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Thursday, April 25th, 2019 AT 11:12 AM
Tiny
AONEAL10515
  • MEMBER
Yes, the master cylinder was bench bleed. I m sure that it s my proportioning valve. My rear wheels are locking up and front wheels keep going. I feel the front wheel brakes engaging after pushing the pedal more than halfway. Once, I get the part this week; I ll let you know if it fixed it.
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Sunday, April 28th, 2019 AT 10:07 AM
Tiny
KEN
  • ADMIN
Sounds good.
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Monday, April 29th, 2019 AT 11:05 AM
Tiny
AONEAL10515
  • MEMBER
Hello,

Proportioning valve was definitely the issue.
Today also found out that my e brake on the passenger side is not engaging. My pedal has way more pressure behind it. Now a lot less play in the brake pedal.I think it s still a little loose because of the e brake cable.

Thank you
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Monday, May 6th, 2019 AT 4:00 PM
Tiny
KEN
  • ADMIN
Good to hear you got it fixed. I would check the adjustment of the brake rod going into the brake booster check that for play.
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Tuesday, May 7th, 2019 AT 11:30 AM

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