2005 Silverado Brake Issue

[dakotart]

2005 Silverado 4.3L 2WD (work truck)

 

Rusted out brake line blew. Replaced 5 lines (2x from master cyl to ABS, 2x from ABS to front wheels, 1x from ABS to rear).

 

Did a bleed at each corner with a vac pump. Not seeing any air but there is still air in the lines. I have been told that you need to have the ABS engage to get the air out of that.

 

Picked up an Autel scanner that has an "Auto bleed" function.

 

The problem I'm having with it is that there is an ABS code of Code C0040 (front right wheel sensor). I attempted to clear the code so I can bleed the brakes but it has not been successful.

 

 

Is there any other way to bleed the brakes to get all of the air out or reset the ABS to remove the code?

 

TIA

[Benner]

Got an 02 yukon and my abs pump is bad so I was really worried about that. I let each line gravity bleed for about 30 minutes at least. Used at least a gallon of brake fluid but the pedal is rock solid. Other way that sometimes works is to get it on a gravel road where you can activate the abs and then rebleed it. But gravity worked great for me. Then finished off with bleeding each wheel

[Trouble Maker]

Other way that sometimes works is to get it on a gravel road where you can activate the abs and then rebleed it.

 

For the same reason he can't reset to code to run a bleed, he probably doesn't have ABS at all. ABS very likely (99%) doesn't work if he has a code for a wheel speed sensor.

Some sensors can be bad (yaw/g) and some ABS systems will disable AYC and TCS but use a more basic ABS, more like ABS pre yaw/g sensors being in cars. But there is not a way I know of or can think of for ABS to work without the wheel speed sensors.

 

Usually the problem with air in ABS is that there will be air in parts of the unit that aren't normally used during regular brake system operation. So, you can do a regular bleed and all is well, but then the next time ABS activates those parts are used and that air will come out into the normally used parts of the system.

 

 

The green and pinkish parts are normally part of the braking circuit, but that red part is only 'open' during some ABS/AYC brake activation.

 

You should be able to get a good bleed on the normally open parts of the brake system even without doing an ABS bleed. So, my feeling is it's a problem with the regular bleed (ABS unit being inline CAN make this more difficult).

 

Or maybe a problem with the parts or install (see below).

Edited November 11, 2019 by Trouble Maker

[Trouble Maker]

Rusted out brake line blew. Replaced 5 lines (2x from master cyl to ABS, 2x from ABS to front wheels, 1x from ABS to rear).

 

Was it originally only 1 line from front to back?

. Maybe it's only a 3 channel system.

 

Did you get lines for your truck or make them?

. If you made them, did you use the same routing or something different?

. You really want to make sure you don't have lines that go above the master cylinder, it's very difficult/impossible to bleed the air out of those.

 

Is there any other way to bleed the brakes to get all of the air out or reset the ABS to remove the code?

 

It's much more complicated than this, but to simply I'll group fault codes into 2 types of codes you'll run into; what I'll call permanent and intermittent.

 

For example for a wheel speed sensor Intermittent problem, there might be a slight problem with the sensor where it will 'read' half of actual speed; 10mph even when you are going 20mph. You will have to drive for the car to detect this problem since at 0mph it will still read 0mph. These you may rest at IG on, or you can reset them. Then since the problem isn't there, you are OK until you drive again and the problem can be detected.

 

A permeant problem is something like an open/short. These can usually be detected even if you aren't driving (or for engine sensors engine running). For these, even if you rest them, the failure checks will immediately detect it right after and trip the fault (code) again. It seems like this is the type of fault you have if you can try to reset it, but it just 'comes back' right away. Unless the OEM/ABS maker has some way to bypass faults (like some factory/service mode) by using a tool like you have, there is no way in normal operation to get around this without fixing the problem; which could be the sensor, some part of the harness; connector (wheel well, sometimes another junction to main harness, into ABS unit) or even in the ABS unit itself.

[Clifford Automotive]

Front right hub is probably bad causing your issue.

[dakotart]

Was it originally only 1 line from front to back?

. Maybe it's only a 3 channel system.

 

Did you get lines for your truck or make them?

. If you made them, did you use the same routing or something different?

. You really want to make sure you don't have lines that go above the master cylinder, it's very difficult/impossible to bleed the air out of those.

 

 

 

It's much more complicated than this, but to simply I'll group fault codes into 2 types of codes you'll run into; what I'll call permanent and intermittent.

 

For example for a wheel speed sensor Intermittent problem, there might be a slight problem with the sensor where it will 'read' half of actual speed; 10mph even when you are going 20mph. You will have to drive for the car to detect this problem since at 0mph it will still read 0mph. These you may rest at IG on, or you can reset them. Then since the problem isn't there, you are OK until you drive again and the problem can be detected.

 

A permeant problem is something like an open/short. These can usually be detected even if you aren't driving (or for engine sensors engine running). For these, even if you rest them, the failure checks will immediately detect it right after and trip the fault (code) again. It seems like this is the type of fault you have if you can try to reset it, but it just 'comes back' right away. Unless the OEM/ABS maker has some way to bypass faults (like some factory/service mode) by using a tool like you have, there is no way in normal operation to get around this without fixing the problem; which could be the sensor, some part of the harness; connector (wheel well, sometimes another junction to main harness, into ABS unit) or even in the ABS unit itself.

 

 

The rear line goes to a T-block that then goes to each rear wheel.

 

I made the new lines and followed the general route except for the right front. No lines go above the master cylinder.

 

It seems to me that even if the sensor had an issue, the code should be able to be cleared long enough to do the auto bleed using the scan tool.

 

Using a vac pump, I got it to have about 1/2 pedal. Maybe I just need to bleed more using this method or the gravity bleed.

 

Thanks

[Trouble Maker]

It seems to me that even if the sensor had an issue, the code should be able to be cleared long enough to do the auto bleed using the scan tool.

 

If it's a persistent and immediately detectable issue, it will (should) trip 'immediately'... all fault detection has some timer to reduce false detecting but usually on the order of <1sec, for something like this probably on the order of 0.x00 sec, fast enough to be called 'immediate'. Open/short is, if the system is designed correctly, is very easy to detect very quickly.

 

You don't want to wait any longer than you have to for fault detection because during that time the system can miss activate. If an ABS system miss-activates too much for too long it can cause 'bad' or even unsafe vehicle dynamics. I had a bad wheel speed sensor on a car once and it wouldn't detect until moving and applying brakes. On the first brake apply that wheel would apply 0 brakes while the others did whatever I was applying. This caused the car to yaw, even though I was driving in a straight line.

[smokin5s]

how are you bleeding the system? Are you using a vacuum pump or having someone press the pedal while you bleed? Also have you bench bled the master cyl? I had to bench bleed my master, then H had someone push on the pedal as I bled the system then went back with the pump using an insane amount of fluid in the process... afterwards I did the ABS bleed then went through the vacuum process again and then ABS bleed again. it was a seriously huge pain but now my brakes are perfect.

[aussiek2000]

Does it actually have air in the system or is the front hub so loose, that its rocking back and forth and eating up your pedal? 99% of these trucks that I did brake lines on did not require ABS bleeding. But if you let the master cylinder run dry, it will need bled separate, and hopefully seals aren't torn

[dakotart]

how are you bleeding the system? Are you using a vacuum pump or having someone press the pedal while you bleed? Also have you bench bled the master cyl? I had to bench bleed my master, then H had someone push on the pedal as I bled the system then went back with the pump using an insane amount of fluid in the process... afterwards I did the ABS bleed then went through the vacuum process again and then ABS bleed again. it was a seriously huge pain but now my brakes are perfect.

 

I have done both. the Master cylinder didn't go dry as far as I could tell.

[dakotart]

Does it actually have air in the system or is the front hub so loose, that its rocking back and forth and eating up your pedal? 99% of these trucks that I did brake lines on did not require ABS bleeding. But if you let the master cylinder run dry, it will need bled separate, and hopefully seals aren't torn

 

After replacing the lines and bleeding at the calipers there were no brakes at all. I bleed the 3 exit lines at the ABS unit and then at calipers again and now have 1/2 pedal (brakes don't engage until pedal is 1/2 way down).

 

I'll check the hub and sensor again when it warms up outside.

[Cordell]

Sounds like it needs an automated bleed procedure to me. Sounds like this old truck has a few problems.

[dakotart]

Sounds like it needs an automated bleed procedure to me. Sounds like this old truck has a few problems.

 

I agree on the auto bleed. Just have to figure out how to clear the ABS code first. It's got some problems for sure.