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Say what?!?
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Discussion Starter · #1 ·
Recently I blew a brake line that runs back to the rear axle. I know that is a common line to rust out. I have already replaced it and manually bled the brakes. However, ever since then when I'm coming to a stop occasionally my ABS will engage. It doesn't always do it but enough that I know something isn't right. My thought is that there is air still in the system and I need to do an ABS bleed procedure with a scan tool. Is this true? I'm a Chrysler tech so I don't have direct access to a computer that will complete that action.

I was also told today that on these older trucks that sometimes rust builds up between the tone wheel and sensor and can cause this issue.

So I guess my question is, do I need to do an ABS bleed function with a computer after blowing a brake line?
 

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I don't know if you need to, but if you think the ABS system needs to be bled, jump on a dirt road and let it cycle some fluid. Sometimes that works.
 

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Reed my teef
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I don't know if you need to, but if you think the ABS system needs to be bled, jump on a dirt road and let it cycle some fluid. Sometimes that works.
like leave a bleeder open a bit and run it for a bit? hows that work?
 

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Say what?!?
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Discussion Starter · #6 ·
I don't know if you need to, but if you think the ABS system needs to be bled, jump on a dirt road and let it cycle some fluid. Sometimes that works.
If there is air in the system still it's just going to go somewhere else in the closed system. That makes no sense at all.

I've read there was a recall about this exact issue. I'm going to make a call in the morning and see if my truck was under that recall.
 

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If you can cycle fluid through the ABS system you may be able to purge any air out. Yes, it won't disappear and you will still need to bleed the brakes. What else does the program tool do?

I threw that out there as general thing, as something I've had luck with and use when changing old fluid or bleeding brakes. Different makes/models might function differently and not be so effective.
 

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Say what?!?
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Discussion Starter · #8 ·
If you can cycle fluid through the ABS system you may be able to purge any air out. Yes, it won't disappear and you will still need to bleed the brakes. What else does the program tool do?

I threw that out there as general thing, as something I've had luck with and use when changing old fluid or bleeding brakes. Different makes/models might function differently and not be so effective.
With my Chrysler scan tool, it will purge the ABS unit when I have a bleeder screw open. You do that after a manual bleed. I also have a BG brake flush machine, just don't have the cap for GM master cylinders. I'm going to get one though next time our BG rep comes in the shop.
 

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gas, grass, and ass
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Pull the ABS sensor and clean it. If it stops then problem solved. If it doesn't then try bleeding it. If thats still not it then replace your whole hub assembly. A new cable and sensor will come with them hub.
 

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Live Action!
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Mine did the same thing after blowing the front left brake line and replacing it.

I just pulled the ABS fuse.


When coming to a stop, just before I was stopped the ABS would kick in and I forget which way but the front wheels would pull to one side. That was about 1-1.5 years ago.

I just replaced the left rear caliper due to it sticking and wiping out the pads on that side otherwise the pad wear has been pretty equal but I knows there must be air in the ABS unit.
 

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bdd
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Are you sure it is because of replacing the brake line? It may be a coincidence, Chevy's eat unit bearings often. I would find someone with snap on solus or similar scanner and see which wheel is causing the issue. You can also grab the front tires at 12 and 6 o clock and feel for a loose bearing. A bad unit bearing can cause the same symptoms as air. I've never had to do a abs bleed on a chev that old.
 

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GM bearings go loose all the time. I always use a tech 2 to perform the simulated bleed. With the power bleeder on it cycles to pump and do each wheel as directed.
Chances are your speed sensor to ring gap is too big due to rust buit up on the bearing housing where the sensor mates. try to remove both ft. sensors and clean the housing to bare metal and lube and reinstall the sensor. Chances are the sensors will break in the housing and you'll have to dig the piece out. if you have an aftermarket bearing it will not accept a factory sensor and work and or vice versa. if you can get a scanner that will show chassis data watch for which ft. sensor goes to 0 earlier than all others. Thats the rat.
Hope this helps.
Mike Z.
 

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It definitely sounds like the speed sensor issue, and there was a recall for that. I wouldn't let a dealer clean the rust though. I've heard too many stories of dealer techs doing it, and letting the debris fall into the hub, resulting in hub failure some miles later. I decided to just pull the fuse, and wait to buy new hubs with the sensors, but I've been waiting 5 years for the hubs to wear out. *shrug*

FWIW, when I had all my hard lines replaced, they simply let it gravity bleed overnight, since I had the ABS disabled (there was concern about what would happen with all the ABS codes still in the computer, even if they replaced the fuse.)
 

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I could see that happening for what that recall paid was a joke. I always put a little piece of paper towel in the hole and pull it strait out with a pic no rot can get in.
GM bearings need no help to fail.
 

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I just replaced all my brake hardlines after a second one blew out.

I used the kit from GM but bought it from Amazon for $60 shipped.

After completing this and bleeding the brakes I no longer have the ABS issue, it would happen every time I came to a stop. ABS would kick in and the front wheels would turn.

So I just pulled the fuse until today. I put it back in and now its all good again.

I would guess there was an air bubble in the lines.

I use a Mityvac to do a preliminary bleed and then have someone pump the pedal for me until I get no air.

I did slam the brake pedal a few times per line to try and get any trapped bubbles out.

Success!
 
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