After being on holiday for a few weeks, I come home and find that the car brake pedal on my (automatic tranmission with ABS brakes) car will no longer spring back up after depressing it. After doing a lot of reading, the problem would appear to be either with the brake booster or the master cylinder. Unfortunately, I can't really tell what might be the issue since I can't find any information that seems to match my specific conditions. There does not appear to be a return spring on the pedal that is missing.
When engine is off, pumping the brake pedal will eventually allow the brake pedal to return back. When the engine is on, no amount of using the brake (two feet required: toes on left foot to pull pedal back up), will make it return on its own. I have verified that the brakes still have excellent holding power. When the car is on and in drive or reverse, the brake still engages. I have not tried driving with it because I live in a high density urban setting.
Based on the above, I think the problem is somewhere in the brake booster or the booster hose. I'd like to diagnose it, but am not sure how. Pressing down on the brake is easy and doesnt feel any harder or softer than it used to be. However, starting the car with my foot on the brake pedal does not "pull" the brake pedal down an extra few inches.
Can I remove the booster hose from the engine side and blow or suck to test for a seal problem? I should only be able to suck air. If I can blow air, I know there is a seal problem. The brake booster hose is not a closed system, is it?
Is there a return spring in the brake booster that could have failed? Is it possible to diagnose this?