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Discussion Starter #1
ever since i have had my 99 K1500 obs the brake pedal has felt soft but after i replaced everything except the abs module the brakes are even worse and barley stop the truck. i had it to the dealer to to have the abs system bleed and they said everything bled fine but they barley work the guy at the dealer said he had no clue what would cause the problem. i am wondering could a bad abs module cause it to feel like their is air in the system?
 

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You might try bleeding them again or having a brake shop instead of dealer do it. did you replace the master cylinder because sometimes that needs to be bled separately from the rest of the system (should be bench bled before going in). I know for the master it can be bled from the connections at the master but I dont remember the proper way as it has been a long time since I have done one. when doing the regular bleeding make sure to go from the furthest wheel and work towards the master (RR, LR, RF, LF)
 

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Discussion Starter #3
I replaced the master cylnder after having the same problem with the old one. The master was bench bled and the entire system was bleed multiple times with no improvement. I finally just got rid of the abs im just waiting for some lines to test it out.
 

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Have you replaced all your brake lines? Have you made sure that your wheel cylinders and calipers are not leaking? Have you checked your proportioning valve and or your combination valve for leaks or bad valves? I suspect a leak somewhere.
 

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Discussion Starter #5
Everything except the abs, and booster has been replaced including the lines and their are no leaks. Even when I got the truck the brakes were not that good and the pedal was soft but not as bad.
 

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look into the booster, since most everything has been done but that and ABS. check the vacuum lines going to the booster for leaks, but the boosters themselves can go bad.
 

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Discussion Starter #7
After a while of thinking I decided to pull the master cylinder off and measure the bore and sure enough it was 1 inch not 1 1/8 like it was suppose to be.
 

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good thinking and hopefully that will fix it all.
 

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Discussion Starter #9
Changed out tthe master and now the brakes feel better than they ever did. Now I just have to try to send the old one back to summit I still have the receipt from allmost a year ago showing that I ordered the right one.
 
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