Hi, our 09 G37 brake pedal will not depress all the way. I took off the emergency brake (it is a manual) and let it roll back while the engine was on. Pressed the brake, and it barley depresses and gave a "shudder" at the same time as if the ABS was kicking in. I tried to drive it and it is very sluggish. The brake light is on. When in neutral, tried to rev the engine and it would only go up to around 2000 RPM.

Not sure what is going on. Never came across this problem before.

Perhaps a vacuum line?

Thank you!

 

Here are a few tests, that might help:

1) With the engine running, repeatedly press the brake pedal. Do you hear a "whoosh" sound?

2) Let the engine run for 1 minute. Turn off engine and with EVERYTHING OFF (you want the cabin as quiet as possible) immediately push the brake pedal fully and quickly. You should hear a slight "whoosh" sound- this is the vacuum reserve in the brake booster.

3) Run the engine for 1 minute. Turn everything off, don't touch anything, and let the car sit for 15-30min. Get in and press the pedal. Do you hear the "whoosh" sound?

If you do not hear a whoosh sound and the pedal is extremely firm after either or all of these tests, then either the vacuum brake booster has failed or, as you suggested, you might have a vacuum hose issue. You can verify engine vacuum by disconnecting the hose at the brake booster while the engine is running.

Keep in mind that even without vacuum brake assist, you can still stop the car, however, the force your foot needs to apply increases exponentially as does your stopping distance.

Did you have any irregular or erratic braking behavior prior to this issue? There is a specific reason I'm asking this...

 

Also check fluid level. IIRC brake light comes on and stays on after disengaging the parking brake if the reservoir is low

 

Typically if the fluid is low and allowed air to enter the system, the pedal would go very soft and go to the floor very easily. The pedal would feel very "squishy/spongy."

However, anything is possible. It never hurts to check the level regardless...