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Internet Tough Guy
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1,014 Posts
Discussion Starter #1
Hey all,

Leaving the dentist today I get in, step down on the brake pedal and as soon as I started the engine the brake pedal dropped to the floor.

I have no ABS light on, only thing on the dash I get is in the vehicle's info area "service brake system". That popped up only after I pumped the brake down a few times, shut off the engine, pumped pedal again until it tightened up, and started the engine... to have the pedal drop to the floor again; then that message came up.

I WASN'T getting any leaks/didn't have any leaks... until I did that final pumping of the pedal. When I did that my entire reservoir leaked out from somewhere. I'm not sure where until I can get under there to take a look.

But, in the mean time... anyone have any ideas on these clues as to what I should look at first?

brake lines? Maybe, but doubtful, why now and all of a sudden...
Any ABS sensors? Maybe, but wouldn't the ABS light be on?
Master cylinder gone? I have no clue...

input appreciated.
 

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Speed Holes
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5,190 Posts
I have a very similar issue, but being I don't have the DIC like yours, mine shows no messages or CEL/codes.

I'm suspecting an inconsistent Master Cylinder. It only does it maybe 2-3 times during a regular 20min drive.
 

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Premium Member
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6,277 Posts
if the res leaked out, look for brake fluid? :roflmao:
 

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Registered
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286 Posts
My 04 silverado did the same thing. The brake line that runs to the rear was leaking near where it tees off to go to both rear calipers


Sent from my iPhone using Tapatalk
 

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Internet Tough Guy
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1,014 Posts
Discussion Starter #6
if the res leaked out, look for brake fluid? :roflmao:
oh thanks, didn't think of that... :throw:

It didn't leak. Wasn't leaking until the pedal dropped to the floor & I shut it off, back on and pumped the pedal.

I was just wondering if anyone had an idea as to WHERE to start since, yes... it leaked AFTER the pumping but I don't know where from.

I guess I should have asked, no leaks until after the pedal dropped and I pumped it, now it leaks from possibly the master cylinder or front driver's area. Oh, wait, I did.
 

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Knuckle Buster
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1,001 Posts
I'm assuming you built the pressure up in the lines with the truck off and blew the cap off the resevoir?
 

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Premium Member
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6,277 Posts
You can't physically find where a leak is?
If not visible, may be into the booster?
this^

cant help you if youre blind. get under the truck and look for a fat wet spot :shrug:
 

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Internet Tough Guy
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1,014 Posts
Discussion Starter #10
this^

cant help you if youre blind. get under the truck and look for a fat wet spot :shrug:

Not blind, just hard to 'get under' the truck and pump the brake myself to see any leaking.

Got creative and setup my phone to record while I pumped the pedal.

I'm thinking the connection of or that line itself has a crack or hole in it there at the arrow.



Now... to find replacements. Anyone run the braided lines?

http://www.ebay.com/itm/Wilwood-Bra...iter_Display:5.3L&hash=item4d286280d5&vxp=mtr
 

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Speed Holes
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5,190 Posts
Yeah I've got Goodridge braided SS lines on both of my current trucks.

I can't tell in the photo, but if that is your leak I'd think it would be extremely wet if you emptied your reservoir there.


Also, do your upper balljoints a favor and flip your UCA's and repress in the BJ from the other side. It'll put the bj at a better angle and have more range of movement when lowered.
 

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Internet Tough Guy
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1,014 Posts
Discussion Starter #12
Yeah I've got Goodridge braided SS lines on both of my current trucks.

I can't tell in the photo, but if that is your leak I'd think it would be extremely wet if you emptied your reservoir there.


Also, do your upper balljoints a favor and flip your UCA's and repress in the BJ from the other side. It'll put the bj at a better angle and have more range of movement when lowered.
Cool, on the SS lines. It is wet all over behind the wheel. I took a video & when I pump the brake you can see it just run down.

I'll have to look into flipping the upper control arm. Thx for that tidbit
 

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Speed Holes
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5,190 Posts
Sounds like you found the problem then, and lucked out it isn't one of your hardlines under the cab.
 

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Registered
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127 Posts
Im having a similar problem just started up. I left work and my brake pedal seemed spongy. It made me push a lot harder for it to actually start slowing down. No light were on. I drove about 30 minutes, going back home.

Then my parking brake light came on, and a message saying "service brake system" like stated above came on. I checked the fluid, it was a little low, so i filled the fluid up. It did not solve the problem what so ever. I can't find a leak anywhere.
 

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I don't own a lowrider
Joined
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4,694 Posts
Im having a similar problem just started up. I left work and my brake pedal seemed spongy. It made me push a lot harder for it to actually start slowing down. No light were on. I drove about 30 minutes, going back home.

Then my parking brake light came on, and a message saying "service brake system" like stated above came on. I checked the fluid, it was a little low, so i filled the fluid up. It did not solve the problem what so ever. I can't find a leak anywhere.
I had a similar problem. Almost no assist on the pedal and had to top the fluid off twice. Turns out, it was leaking into the booster from the master. It must have been doing it slowly for awhile because the booster was extremely corroded on the bottom. Once everything was replaced, along with the calipers and hoses, all is well.
 

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Registered
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I had a similar problem. Almost no assist on the pedal and had to top the fluid off twice. Turns out, it was leaking into the booster from the master. It must have been doing it slowly for awhile because the booster was extremely corroded on the bottom. Once everything was replaced, along with the calipers and hoses, all is well.

How much did it cost you? If you don't mind me asking. Also, is there a way I can check this without taking to a dealer?
 

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I don't own a lowrider
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4,694 Posts
How much did it cost you? If you don't mind me asking. Also, is there a way I can check this without taking to a dealer?
I think I spent about $500 replacing everything. When I pulled the booster off the firewall I could hear sloshing. Not sure how you could check with everything still connected.
 

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Registered
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I think I spent about $500 replacing everything. When I pulled the booster off the firewall I could hear sloshing. Not sure how you could check with everything still connected.

Refilling the brake fluid didn't fix it, but I parked it for about an hour. (Don't know if this had an effect.) but I was pulling in my driveway, and hit the brake all the way down until it clicked and then that reset the sensor I guess. The lights went off and the brakes started working again.
 

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I don't own a lowrider
Joined
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4,694 Posts
Refilling the brake fluid didn't fix it, but I parked it for about an hour. (Don't know if this had an effect.) but I was pulling in my driveway, and hit the brake all the way down until it clicked and then that reset the sensor I guess. The lights went off and the brakes started working again.
Brake fluid doesn't just disappear. It has to be going somewhere. If your brake pedal hit the floor it sounds like the system is ruptured somewhere or has a large amount of air in it. I wouldn't drive the truck until you fix it.
 
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