2003 Chevy Tahoe Z71 here. This morning as I was driving to work I noticed my brakes were a little unresponsive. I recently checked the pads/rotors and they are in good shape. When I push the pedal down, it seems like I can push it further than usual. I tested it going about ~35-40 and 'slammed' on my brakes the way I would if a deer were to dart out in front of me, and stoppage was pretty much as expected. However, this caused the "Service Brakes" to turn on and the cars warning system to start beeping at me. When I plugged in a code reader, it didn't detect anything, the error has gone away, and I didn't notice the same issues with the brakes.

Any ideas here? Possibly some air here, maybe an issue with the brake booster. My first idea would be to replace the lines, as I understand it is possible that even if I don't have an external leak it is possible that there is a leak in one of the inner tubes.

Thanks in advance.

  • 2
    Have you checked the level of the brake fluid reservoir?
    – Martin
    Commented Aug 24, 2016 at 11:38
  • 2
    Sounds like a leak somewhere to me. Check your lines, hoses, calipers and wheel cylinders (if equipped). Look for set spots. Have someone hit the pedal and look for drips. Do not let the master run dry or you will have some fun trying to bleed the entire system.
    – rpmerf
    Commented Aug 24, 2016 at 14:25
  • Does this have Hydroboost or vacuum actuated power assist? Commented Aug 24, 2016 at 14:41
  • When you stop with your foot on the brake, does the car slowly creep forward after a few seconds, requiring you to press again on the pedal? If so, that would indicate a worn out brake manifold. When putting a new one on, bench-bleed it unless you like trying to sort out brake issues..
    – PeteCon
    Commented Aug 24, 2016 at 19:42
  • problem solved, just needed to get underneath it Commented Aug 25, 2016 at 11:45

2 Answers 2


While having some one depress the brakes inspect each of the rubber flex hoses at the wheel corners. Look for any sign of bulging. Hoses age with repeated expansion and contraction form brakes being applied.
This eventually causes bulges in the inner hose part which requires extra fluid to make up for the extra space and hence a slow petal depression. The Service Brake light and alarm relates to this as an expanding hose on one wheel during extreme hard stop would cause a shift in the pressure between sections, which would clear on pressure balance return. IN your vehicle these clear with power (ignition) off and on, so not stored and readable unless read when active. You might never see a leak until it is to late and the hose bursts. If hoses are not the issue your next most likely suspect is the ABS motor pump or control circuitry.

  • The relevant phrase here is "Until it is to late and the hose bursts". Once I put more brake fluid in there, I watched it pouring out almost immediately. One of the main lines running off the master cylinder rusted through. Commented Aug 25, 2016 at 11:47
  • Reminds me of an old 60s VW bug, brakes worked very slowly. Kept pumping and bleeding but never improvement. After adding several weeks of fluid refills and bleeding but no sign of fluid loss I noticed a small discoloration at driver seat carpet, wiping it up the smell was obvious, brake fluid. With a telescopic camera I looked in the center tunnel and found a rusty brake line leaking into the tunnel with a large puddle of fluid. Another few miles and the line would have totally burst. VWs of that age have no front rear isolation, it would have been complete non-stopping. Commented Aug 25, 2016 at 15:16

Look at the level of the brake fluid. If its low, top it up and pump the pedal to check for leaks. If you cannot find leak anywhere, most probably the brake fluid is leaked into the booster pump.

This can be very dangerous, you may end up at some other vehicles rear end.

Get you master pump and booster pump checked and replaced.

  • booster pumps are totally not needed. Just gotta have a heavy foot Commented Sep 14, 2016 at 12:04
  • True... Booster pumps are created to assist women drivers... Their foot is always light. Commented Sep 14, 2016 at 12:23

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