I have a 2003 tacoma 4x4 xtracab and I've been having problems with my rear brakes slowly starting to lock up on me (after a few miles of driving and using the brakes). I popped the drums and found one of the wheel cylinders leaking, so I replaced it and redid the rear brakes shoes.
I thought this might fix the problem, but it's still there. Drove the truck after doing the fixes and the rear wheels locked up again after a few miles of driving and breaking.
I'm going to pop the drums again and check the star adjuster and parking brake cable/assembly. I checked them before putting the drum on last time and everything seems ok.
Any ideas of what the issue might be? Master cylinder? Brake lines? Proportioning valve? It seems like they are fine when the brakes are cold, but once it heats up the brakes lock on. Maybe somehow the brake fluid isn't getting out the wheel cylinder. Not sure where else to look........