'05 Z71 Front Brake Problem

[NelBosco]

I have an '05 crew cab 4wd Z71 with 1,000 miles and tomorrow I am bringing it in AGAIN for the same problem, my front brakes are not releasing. The first time it happened was at 400 miles and in traffic. The calipers did not release and just getting to the side of the road was a chore. Once I did pull over I noticed that burning brake smell and they were actually smoking. After I pumped the brakes they finaly released brought it in and they replaced the drivers caliper because there was no evidence on the passenger side caliper (but I doubt that). This weekend I was driving at highway speeds and began to notice something was not right as if the engine was laboring and a slight vibration was coming up into the steering wheel. I thought maube I have a tire going down so I pulled off at the next available exit and noticed the burning brake smell again. Coming from both the driver side and passenger side. It was not as severe as the first time and it has only happened these two time, I think.

 

The first time it was in the service manger thought it could be the caliper return lines but both checked ok.

 

What controls the hydraulic pressure or what could prevent the caliper from releasing? Have you seen this before? The recall on the booster does not address this and I have not seen any other posts similar to what i am experiencing.

 

Thanks.

[GM-Tech]

I would suspect the booster. Wouldn't be the first. I'm not aware of any booster recall for '05 Silverado, so I'm not sure what your mention of that is all about.

[NelBosco]

My mistake it is the brake booster pressure accumulator that is being recalled

[GM-Tech]

My mistake it is the brake booster pressure accumulator that is being recalled

 

Okay, I know about that one. That wouldn't have any bearing on your problem, and even if there's a recall (or not) doesn't mean it can't fail in some other manner.

 

If you can get this problem to occur, it should be easy enough to narrow down. With the brakes binding, just loosen the master on the booster. If the brakes release, the booster is keeping the master slightly applied. In the "old days" a brake switch misadjusted could cause this, but they don't use that kind of brake switch on most applications nowadays.

[NelBosco]

If you can get this problem to occur, it should be easy enough to narrow down. With the brakes binding, just loosen the master on the booster. If the brakes release, the booster is keeping the master slightly applied. In the "old days" a brake switch misadjusted could cause this, but they don't use that kind of brake switch on most applications nowadays.

 

<{POST_SNAPBACK}>

 

 

 

 

What do you mean "loosen the master on the booster", should I relieve the vacuum on the bosster?

 

Thanks again for your input

[GM-Tech]

What do you mean "loosen the master on the booster", should I relieve the vacuum on the bosster? 

 

The master cylinder is bolted to the booster. Loosen the two nuts that hold it. You don't have to take them all the way off, just loosen them quite a bit. If this the problem, the master will only have to be able to move a fraction of an inch away from the booster to release the brakes.

[NelBosco]

Update:

 

My dealer located a recent bulletin but it is not a TSB he called something else that I do not recall.

 

Anyway it was for a "brake drag and highway vibration". They performed the service and replaced the booster.... so far all is good.

[gregseay]

I have an '05 crew cab 4wd Z71 with 1,000 miles and tomorrow I am bringing it in AGAIN for the same problem, my front brakes are not releasing.  The first time it happened was at 400 miles and in traffic.  The calipers did not release and just getting to the side of the road was a chore.  Once I did pull over I noticed that burning brake smell and they were actually smoking.  After I pumped the brakes they finaly released brought it in and they replaced the drivers caliper because there was no evidence on the passenger side caliper (but I doubt that).  This weekend I was driving at highway speeds and began to notice something was not right as if the engine was laboring and a slight vibration was coming up into the steering wheel.  I thought maube I have a tire going down so I pulled off at the next available exit and noticed the burning brake smell again.  Coming from both the driver side and passenger side.  It was not as severe as the first time and it has only happened these two time, I think.

 

The first time it was in the service manger thought it could be the caliper return lines but both checked ok.

 

What controls the hydraulic pressure or what could prevent the caliper from releasing?  Have you seen this before? The recall on the booster does not address this and I have not seen any other posts similar to what i am experiencing.

 

Thanks.

 

<{POST_SNAPBACK}>

 

 

[gregseay]

I have an '05 crew cab 4wd Z71 with 1,000 miles and tomorrow I am bringing it in AGAIN for the same problem, my front brakes are not releasing.  The first time it happened was at 400 miles and in traffic.  The calipers did not release and just getting to the side of the road was a chore.  Once I did pull over I noticed that burning brake smell and they were actually smoking.  After I pumped the brakes they finaly released brought it in and they replaced the drivers caliper because there was no evidence on the passenger side caliper (but I doubt that).  This weekend I was driving at highway speeds and began to notice something was not right as if the engine was laboring and a slight vibration was coming up into the steering wheel.  I thought maube I have a tire going down so I pulled off at the next available exit and noticed the burning brake smell again.  Coming from both the driver side and passenger side.  It was not as severe as the first time and it has only happened these two time, I think.

 

The first time it was in the service manger thought it could be the caliper return lines but both checked ok.

 

What controls the hydraulic pressure or what could prevent the caliper from releasing?  Have you seen this before? The recall on the booster does not address this and I have not seen any other posts similar to what i am experiencing.

 

Thanks.

 

<{POST_SNAPBACK}>

 

 

 

<{POST_SNAPBACK}>

 

 

 

i have 06 crew cab z71 w/ similar problem vib in steering wheel bad front brakes not releasing all the way already had right caliper replaced still happening but does not happen when i take it to the dealer so they dont know what to do

[ChevyTech007]

This might apply:

 

Subject: Brake Drag, Pull, Grab, Wear and/or Highway Speed Vibration - keywords assist pad pedal pulsation rotor wheel wear #PIT3685A - (09/29/2005)

 

 

 

Models: 2005-2006 Chevrolet Silverado 1500

 

2005-2006 GMC Sierra 1500

 

With RPO JF3 or JF7

 

Built before Sept. 1, 2005

 

 

 

 

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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

 

Condition/Concern:

Owners may comment on a brake drag, pull, grab, wear, and/or highway speed vibration. This could be caused by distortion of the vacuum boosters floating control valve. Under high engine vacuum conditions, the brake booster may self apply which could lead to a brake drag. In some cases, a concern of brake pulsation may be noticed due to the brake drag.

 

Note: When performing diagnostics, be aware this concern is caused by distortion of the floating control valve under high engine vacuum and if the engine is shut off vacuum will be removed and the concern will go away.

 

Recommendation/Instructions:

To help isolate the concern to the brake booster, pull up lightly on the brake pedal when the concern occurs. If the condition goes away replace the brake booster with updated part number 15840835. This new brake booster was implemented into production September 1, 2005.

 

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.