03 Brakes

DLP · Post by **DLP** » Mon Sep 18, 2006 2:21 pm

Just hooked up with the site today. Like a kid with a new comic book, I did a lot of reading! I have a problem with my brakes on the 03 CC. At 60,000 I replaced all 4 rotors and brake pads. They didn't need replacing because they were still half the thickness as the new pads and the rotors had no gulling or noticable warping. I had just built a trailer that hauls my popup and quads so I wanted to be safe with the brakes. After replacing the pads and rotors I got in the truck to pump the pedal to close the pistons. The pedel went to the floor a couple times before It went hard. Now the pedal will go to the floor when I hold it down hard. I have since put about 10,000 miles on it . The brakes work fine and I don't have any problems stopping but don't like the pedel travel. I changed out the master cylinder, both front and rear calipers, new juice and took it to two different shops to have them bleed the lines. Still poor pedal hardness. If I pump the pedal it will get hard but if I hold it down hard it will creep to the floor. Sure sounded like a master cylinder to me. Is there anything with the ABS to cause this? Thanks

F9K9 · Post by **F9K9** » Mon Sep 18, 2006 2:41 pm

Welcome to the site. Steve, HenryJ and many more will have some good suggestions when they see the post. Something is leaking off in my opinion but, I have been removed from wrenching for several years. After owning a '97 ZR2 and planning stops 1/2 mile ahead I have been thrilled with my CC's brakes and have had no trouble. I am only at 23K so, I know my troubles lay ahead.

You'll get them solved here one way or the other

Post by **HenryJ** » Mon Sep 18, 2006 2:49 pm

Wow! Second post and you smack us with a tough one

What about the power brake booster? Check it for a leak. If you replaced a leaky master cylinder it could have damaged the booster.

It sounds like you have all the right ideas. Air in the system, or a bad master cylinder would be my guesses too. New parts can be faulty. Don't assume they can not be a problem since they are "new".

Some things to check might be the pushrod adjustment for the master cylinder. Too tight and it will not fully release (not your problem) , and too loose and it will have excessive travel.

It might be possible that you have air trapped in the ABS system I suppose? I have heard that cycling the ABS with a scan tool may be required to properly bleed the ABS system. I have not had to do that. Just something that I heard or read somewhere. It may not even be applicable to our system.

Kind of hard to diagnose long distance. It is worth further investigation though. Brakes are one of those things you do want working correctly.

04crewvt · Post by **04crewvt** » Mon Sep 18, 2006 3:38 pm

04crewvt wrote: I am also having them check the brakes they grab when wet and the pedal keeps sinking to the floor when I depress the pedal and hold it down.

04crewvt wrote:Here is the info as of today.
Dealer is ordering me a new ,brake vacuum booster,They suspect a vaccuum leak in the booster is the brake problem

04crewvt wrote: They also found an internal vacuum leak in the brake booster and replaced unit, brakes much better now.

This may be your problem.

Post by **HenryJ** » Mon Sep 18, 2006 3:49 pm

04crewvt wrote:
04crewvt wrote:... found an internal vacuum leak in the brake booster and replaced unit, brakes much better now.
This may be your problem.

Ok, so maybe this was not such a hard problem to find?

That sounds like the winner

04crewvt · Post by **04crewvt** » Mon Sep 18, 2006 3:56 pm

At least it will be a good place to start.

DLP · Post by **DLP** » Mon Sep 18, 2006 4:11 pm

Thanks for the ideas. Like I mentioned, I have 10,000 miles including a trip pulling the trailer from Michigan to Yellow Stone and back. No issues other than the pedal feels soft. I look forward to talking with you folks.

04crewvt · Post by **04crewvt** » Mon Sep 18, 2006 4:21 pm

Other thing to check this is the official way GM wants the brakes bleed.

Hydraulic Brake System Bleeding

1. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
2. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
3. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, you must perform the following steps:
1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level; if necessary add Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm, if cap removal is necessary.
2. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe from the front port of the brake master cylinder.
3. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
4. Reconnect the brake pipe to the master cylinder port and tighten securely.
5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
6. Loosen the same brake pipe to purge air from the open port of the master cylinder.
7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
8. Wait 15 seconds, then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
9. With the front brake pipe installed securely to the master cylinder, (after all air has been purged from the front port of the master cylinder), loosen and separate the rear brake pipe from the master cylinder, then repeat steps 3.3-3.8.
10. After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.
4. Fill the brake master cylinder reservoir with Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. Ensure that the brake master cylinder reservoir remains at least half-full during this bleeding procedure; add fluid as needed to maintain the proper level.
5. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm, when cap removal is necessary. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve, then install a transparent hose over the end of the bleeder valve.
6. Submerge the open end of the transparent hose into a transparent container partially filled with Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
7. Have an assistant slowly depress the brake pedal fully and maintain pedal position.
8. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
9. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
10. Wait 15 seconds, then repeat steps 7-9 until all air is purged from the same wheel hydraulic circuit.
11. With the right rear wheel hydraulic circuit bleeder valve tightened securely, (after all air has been purged from the right rear hydraulic circuit), install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve, install a transparent hose over the end of the bleeder valve, then repeat steps 6-10.
12. With the left rear wheel hydraulic circuit bleeder valve tightened securely, (after all air has been purged from the left rear hydraulic circuit), install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve, install a transparent hose over the end of the bleeder valve, then repeat steps 6-10.
13. With the right front wheel hydraulic circuit bleeder valve tightened securely, (after all air has been purged from the right front hydraulic circuit), install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve, install a transparent hose over the end of the bleeder valve, then repeat steps 6-10.
14. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
15. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
16. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
17. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still feels spongy after repeating the bleeding procedure, perform the following steps:
1. Inspect the brake system for external leaks. Refer to .
2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.
18. Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
19. If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired. Refer to .

border man · Post by **border man** » Mon Sep 18, 2006 4:23 pm

Welcome to the site!!

Do you have any pics of your trailer setup??

border man · Post by **border man** » Mon Sep 18, 2006 4:27 pm

10-3 (disregard) my last

Snoman002 · Post by **Snoman002** » Mon Sep 18, 2006 5:04 pm

04crewvt wrote:
04crewvt wrote: I am also having them check the brakes they grab when wet and the pedal keeps sinking to the floor when I depress the pedal and hold it down.

04crewvt wrote:Here is the info as of today.
Dealer is ordering me a new ,brake vacuum booster,They suspect a vaccuum leak in the booster is the brake problem

04crewvt wrote: They also found an internal vacuum leak in the brake booster and replaced unit, brakes much better now.
This may be your problem.

Hmmm, interesting. It's funny that a leaking booster could cause a soft pedal feel.

I have this same issue with our Bravada and though I'm not worried about it, it's still "one of those things", if you know what I mean.

I do have one question for you. When you did the brakes did you push the caliper piston back in with or without opening the bleeder? I did mine without opening the bleeder, just popped the cap off the master cylinder and slowly pushed the piston back in.

DLP · Post by **DLP** » Mon Sep 18, 2006 6:22 pm

When I compressed the pistons, I didn't pop the cap. Fluid did leek out of the resivar.

Another picture of the trailer.

Post by **Walt** » Mon Sep 18, 2006 6:43 pm

That trailer setup looks pretty sharp. I take it you're pretty good at welding?

Rusty Shackleford · Post by **Rusty Shackleford** » Tue Sep 19, 2006 3:36 am

You may want to try an ABS stop on a gravel road..just find a road that doesnt have much traffic on it, get going and mash the brakes hard. Every time I do a brake job at work and the pedal feels soft my foreman takes it out, does an ABS stop and it brings the pedal right up.

Snoman002 · Post by **Snoman002** » Tue Sep 19, 2006 12:12 pm

Funny thing, the wife just called and the ABS light just turned on.

Still havn't looked at the truck so it could be something stupid, but it's funny it happened today.

Post by **Walt** » Tue Sep 19, 2006 1:07 pm

Have you checked the fluid bearings in the brake calipers?

Just kidding

But seriously, be on the lookout for other problems with the ABS light. Vacuum, 4wd, etc.... They should rename that light from "ABS" to "Guess what?"

kwalsh · Post by **kwalsh** » Tue Sep 19, 2006 5:21 pm

How about that flux capacitor modulating unit?