Unusual Brake Problem
 

Recently started experiencing an odd brake problem, searched for similar symptoms here but couldn’t find anything. Bit of history 1st.
The MIL/VSC/TRAC lights have been illuminated for some time. I’ve had the codes read on several occasions and it has consistently been the MAF sensor. Tried cleaning it, no luck, but the truck runs fine so I haven’t bothered to do much else. About 20,000 miles back the Brake warning light came on. I checked and the pads were nearing their end so I replaced all four sets, completely flushed the system with new fluid, nothing was stuck or hung up so I buttoned it all back together and while the light didn’t go away, the brakes work great, ABS engaged when needed, so again I moved on with life. FWIW I used the brake pump to bleed the rears as detailed here.

Fast forward to last weekend, we’ve had a lot of rain recently in central Florida and one morning I got in to drive to work and noticed the Brake light was gone, but the brakes were snatchy and the pedal was vibrating. I figured the brakes was wet from storms overnight, and after a couple of stops the Brake light came back and the brakes started working well again. Brake fluid res is still full.


TL: DR Brakes are snatchy and pedal is rough when Brake light is off, brakes work fine when Brake light is on, MIL/VSC/TRAC all on.

scan the car and post the codes, you may need an abs capable code reader

Autozone code reader is telling me MAF sensor again, so I cleaned it again. However I went ahead and dug in to the brakes and sure enough the left rear wheel bearing seems likes it’s giving up the ship. Inside of the rim, as well as the disc, caliper and dust shield are all coated in a wet grime. I was able to wobble the tire left-right ever so slightly prior to removing it. I went ahead and took the wheel speed sensor off and cleaned it but like everything else back there it was coated in mung. Bearings are beyond my ken, so off to a shop it goes and once they've been replaced (I’ll do both rears) I can replace the rotor and sensor at home since I cannot help but think they are contaminated also.
Can’t complain, 230,000 miles on the OEM wheel bearings isn’t bad.

Local shop confirmed the bearing and seal failure, as well as the rotor and ABS sensor. Le' sigh, its only money, right?