Over the past few mornings, it has been colder than normal here (~50F). When I make a complete stop, the brake pedal feels "crunchy" as the car is almost stopped. Shuttle valve switch code also sometimes comes on (but upon further diagnosis, the computer reads the signals correctly with no abnormalities). I am currently suspecting a master cylinder on its way out or the ABS modulator. However, I want to try a brake bleed in the hopes that its just air (from what, I don't know) or bad fluid.

Brake work that has been done:

Rebuilt master cylinder 4k miles ago
New rotors and pads 3k miles ago
Option B shuttle valve switch 7k miles ago

Any ideas? Maybe this is normal and I just started noticing? The weird thing about it is that it only happens in the mornings.
Thanks.

 

I've never heard of this issue, very strange. I'd also actually look at the pedal. Its a long shot, but something could've gotten in its way or something to be causing that. Second guess would be master cylinder, as you said,.

 

If your getting a crunching sound I would check pads, caliper mounts lug nuts hub.

 

All valid points. I am going to flush the fluid today anyway, so a brake inspection shouldn't be too hard while the wheels are off. Brake pads make sense as it is possible that they might need a little copper grease.

Alex- it's funny that you mention the brake pedal itself as I just remembered that I have had some issues with it in the past. About a year ago, I had to put some silicone grease on the pivot point because it had started to squeak. So I will check that out as well.

Thanks again guys.