Chevy-GMC pickups brakes

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  #1  
Old 09-04-13, 04:15 PM
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Chevy-GMC pickups brakes

2004 GMC 4x4,antilock brakes

Does anybody here know of a fix for earlier models, like above,brake problems?

Apparently this has been a dangerous issue for some years especially on the
4x4s.

I lost a brake line,and after it was replaced ,and bled,sometimes the brakes were low,or had a chatter when applied. Mechanic stumped

Thanks
 
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Old 09-04-13, 05:40 PM
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You need to blead the ABS system properly... When I replaced the line at the ABS modual I did not have the bleeding tool...

I took the truck on soft dirt and locked them up to activate several times.. Then I re bleed and the pedal came up to where its supposed to...


Mechanic stumped
Try another mechanic....
 
  #3  
Old 09-05-13, 06:09 AM
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Thanks for your reply. I'll pass that along to my mechanic.

Apparently this issue has been going on for over 10 yrs in GMC ,and Chevy line..
 
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Old 09-05-13, 07:40 AM
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Oh yeah there was a recall ... Not sure what the fix was... Something with the module...
 
  #5  
Old 09-05-13, 07:57 AM
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As mentioned GM products did have an ongoing issue with ABS function. It was based on power relays failing in the control module and the early resolution was to replace the module. I had mine rebuilt with great success. There are other possibilities though. If a wheel speed sensor cable is intermittently open or shorted the ABS unit will respond to whatever is sent so there is a possibility. You said you had a brake line replaced, could a sensor have been upset during that process? That would or at least could cause an intermittent issue with brake function, air in the system would be something you might feel during initial brake application more continuously. As for bleeding the ABS system, a power bleeder is needed to do a proper air purge. I know there are so many old timers saying oh hell I can do it with a pop bottle and some wiper hose but I can say I have seen that method not work and poor brake function after repairs is something everyone in the business wants to avoid.
 
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Old 09-05-13, 08:51 AM
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Thanks to all. I'll mention all the 'maybe's' to my mechanic.

Appreciate all of you taking the time to offer your help.
 
  #7  
Old 09-07-13, 10:19 AM
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Update;
A corroded/rusted brake sensor seems to be the culprit.

My Mechanic cleaned it two days ago, and brakes are back to normal.
He wants me to drive it for awhile to make sure it is indeed fixed.

Thanks to everyone who posted.
 
  #8  
Old 09-07-13, 10:31 AM
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Great news.......Glad it worked out...
 
  #9  
Old 09-08-13, 03:08 PM
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Tijoe
I have a similar problem on my 99 silverado.
I get the abs light about fifty percent of the time after rear pads replaced three years ago.
I cannot find the rear wheel sensors.?????? Gardnerb
 
  #10  
Old 09-08-13, 03:26 PM
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I cannot find the rear wheel sensors.??????
Its usually in a sensor in the rear differential,,, Get a Haynes manual it will tell you.
 
  #11  
Old 09-10-13, 05:37 PM
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A 99 would have a single sensor usually mounted on the pumpkin area somewhere and to the front sensing off the input shaft or pinion shaft. Look for the wires coming down from the chassis.
 
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