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Discussion Starter #1
I was driving my 2020 Equinox and got off the interstate. On the exit my break pedal became next to impossible to push. I can push down barely and it stops really slow. Breaks are working fine with adaptive cruise control but manual pushing the break pedal is difficult. Service Brake assist light came on. Error code P0556. I still have some warranty left, and got an appointment tomorrow but wanted to check if anyone has any suggestions to what may be wrong.
 

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Possibly a bad power brake booster or vacuum hose.


Symptoms of a Failing Power Brake Booster:
  • Stiff brake pedal that is extremely hard to push
  • Longer stopping distance
  • Engine stalls when brakes are applied
Prior to replacing your Power Brake Booster:
  • Ensure the Vacuum Hose is properly connected and not loose
  • Check the Vacuum Hose for a blockage or leak
  • Inspect the Check Valve for cracks, looseness or damage
Testing your Power Brake Booster:
  • With the engine off, pump the brakes 5-6 times
  • Turn the engine on while pushing down lightly on the brake pedal
  • If your brake booster is working, the pedal will sink down about ¼”
  • If your brake booster is not working, nothing will happen or the brake pedal will push back against your foot
 

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Discussion Starter #4
Possibly a bad power brake booster or vacuum hose.


Symptoms of a Failing Power Brake Booster:
  • Stiff brake pedal that is extremely hard to push
  • Longer stopping distance
  • Engine stalls when brakes are applied
Prior to replacing your Power Brake Booster:
  • Ensure the Vacuum Hose is properly connected and not loose
  • Check the Vacuum Hose for a blockage or leak
  • Inspect the Check Valve for cracks, looseness or damage
Testing your Power Brake Booster:
  • With the engine off, pump the brakes 5-6 times
  • Turn the engine on while pushing down lightly on the brake pedal
  • If your brake booster is working, the pedal will sink down about ¼”
  • If your brake booster is not working, nothing will happen or the brake pedal will push back against your foot
Break booster must be bad then. Cannot do any of the test to work. I am seeing there is a class action against GM for bad brake boosters. Thanks
 

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Discussion Starter #5
At the dealership now, they just informed me the vacuum pump failed. They have the part, but got to get it off to see if the gears also broke. They don't have the gears instock and will need to order those is so.
 

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Discussion Starter #6
Update. The gears inside was fine. Officially from the paperwork it says the locking tange that locks the vacuum pump to the camshaft was cracked. Not really sure what the locking tange is in the vacuum pump. It is fixed and back to normal, no idea how it could have cracked.
 

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Thanks for the updates

2014 Terrain SLE-2 /Silver Sky Metallic / 3.6 L V6 / AWD / Pioneer Stereo / 85,600 miles as of March 2021
 
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