I posted this somewhere else, figured it might be better here for longevity:
First a note: this is only necessary if you get air in your ABS system like your master runs dry and air goes down the line to settle in the ABS pump and valve system. Normally you only need to bleed each caliper to get air bubbles out that formed from old (water soaked) brake fluid or overheating the fluid and air bubbles forming. A normal brake bleed will never get air bubbles out of the ABS system because the valves need to be open while you bleed and the only way to do that is have the car open the ABS valves while you bleed.
In the ABS ECU is a software program that will hold the two left side ABS vales open while you bleed, and for the right side will actually pump and cycle the ABS vales in a pattern to "shake" the bubbles thru the ABS system and actually pump out a little fluid on its own. Before the tech tool companies cracked the GM tech software, the only way to activate this program was at the dealer with their Tech2 tool.
I bought a Foxwell NT530 tool with the "GM" software package. When not used for GM cars, it works like a normal ODB2 tool for all other cars. But for GM you can run all/most of the dealer functions in the tech2 tool they have at the dealer. I think on this model you can add up to 4 manufacturers and after setup I paid another $40ish to add BMW for my other car. Initially the ABS pump bleed did not work on my car, but it did work on my friend's Camaro. After two weeks of emailing logs to Foxwell and them emailing me back test programs, we got the Holden G8 added to the GM software and now it works.
If you dont have air in your ABS system, you dont need this tool/software, you can just bleed your brakes as you normally do to get air out of your calipers. But I did the caliper upgrades to CTSv units as well as brake lines and my system was dry. So I did get air in my ABS pump and bled my brakes over 7 times and never got a good feeling pedal at all. The only way to get the ABS valves to open and self pump to get the air out is going to the dealer for them to use the tech2 or buy a software tool that will do it. And make sure they dont do a regular bleed like they would do 99% of the time, they need to use the tech2 to bleed the ABS system as they bleed.
Basically you are bleeding the brakes as you normally would (having someone pump the brake pedal as you open close bleeers, or a pressure bleeder on the master, or a vac bleeder on each caliper) but you do it when the software tells you to so it can hold open the ABS valves or vibrate them open and closed while you bleed.
How:
Go to the software you're using and start the ABS brake bleed procedure. On the Foxwell you go to GM software, let it find your VIN, go to brake section, go to special applications, and select ABS brake bleed. It will tell you to "open the bleeder for front left and pump brake pedal". Since the software waits after each corner, you can jack up each corner of the car one at a time and removed the wheels one at a time, no need to raise the whole car and take all four tires off. Now you bleed the front left as normal, while it is holding open the ABS valves. Click next and you get "open the bleeder for rear left and pump brake pedal". Now you bleed the left driver side as you normally would. Hit next and "open bleeder for front right hit ok when ready". For the right side the software will actually cycle the ABS pump for a few min. So you crack open the bleeder (I use a hose into a bucket on the bleeder) and hit ok. Now you will hear the car's ABS pump makes all kinda of weird rhythmic sounds like its singing too you and some fluid will come out of the hose. This is where I'm not sure I'm doing it correctly. I decided to let the car do its thing, and then bleed that corner as normal figuring if any bubbles came out of the ABS pump there may be air in that caliper now. I was thinking maybe I was supposed to bleed WHILE the car was pumping the ABS? But that makes less sense to me. So after the rhythmic vibrating I bled as normal and hit next. Then you do the same thing for the last screen on the tool, "open bleeder for right rear" and do the ABS pump thing again then bleed after.
I was slightly disapointed my brake pedal was not rock hard like I was expecting (it was moosh before I did this) but then when I actually stopped the car I had so much brake control and feeling while I was braking it was like a new car. Before I got the air out of the system there was a numb dead spot in the middle of the pedal and it was very hard to glide brake up to a stop sign or red light. I'm sure the dealer ABS bleed procedure is in the shop manuals I should probably check if you're supposed to bleed while the ABS pump is pumping fluid thru or after.
First a note: this is only necessary if you get air in your ABS system like your master runs dry and air goes down the line to settle in the ABS pump and valve system. Normally you only need to bleed each caliper to get air bubbles out that formed from old (water soaked) brake fluid or overheating the fluid and air bubbles forming. A normal brake bleed will never get air bubbles out of the ABS system because the valves need to be open while you bleed and the only way to do that is have the car open the ABS valves while you bleed.
In the ABS ECU is a software program that will hold the two left side ABS vales open while you bleed, and for the right side will actually pump and cycle the ABS vales in a pattern to "shake" the bubbles thru the ABS system and actually pump out a little fluid on its own. Before the tech tool companies cracked the GM tech software, the only way to activate this program was at the dealer with their Tech2 tool.
I bought a Foxwell NT530 tool with the "GM" software package. When not used for GM cars, it works like a normal ODB2 tool for all other cars. But for GM you can run all/most of the dealer functions in the tech2 tool they have at the dealer. I think on this model you can add up to 4 manufacturers and after setup I paid another $40ish to add BMW for my other car. Initially the ABS pump bleed did not work on my car, but it did work on my friend's Camaro. After two weeks of emailing logs to Foxwell and them emailing me back test programs, we got the Holden G8 added to the GM software and now it works.
If you dont have air in your ABS system, you dont need this tool/software, you can just bleed your brakes as you normally do to get air out of your calipers. But I did the caliper upgrades to CTSv units as well as brake lines and my system was dry. So I did get air in my ABS pump and bled my brakes over 7 times and never got a good feeling pedal at all. The only way to get the ABS valves to open and self pump to get the air out is going to the dealer for them to use the tech2 or buy a software tool that will do it. And make sure they dont do a regular bleed like they would do 99% of the time, they need to use the tech2 to bleed the ABS system as they bleed.
Basically you are bleeding the brakes as you normally would (having someone pump the brake pedal as you open close bleeers, or a pressure bleeder on the master, or a vac bleeder on each caliper) but you do it when the software tells you to so it can hold open the ABS valves or vibrate them open and closed while you bleed.
How:
Go to the software you're using and start the ABS brake bleed procedure. On the Foxwell you go to GM software, let it find your VIN, go to brake section, go to special applications, and select ABS brake bleed. It will tell you to "open the bleeder for front left and pump brake pedal". Since the software waits after each corner, you can jack up each corner of the car one at a time and removed the wheels one at a time, no need to raise the whole car and take all four tires off. Now you bleed the front left as normal, while it is holding open the ABS valves. Click next and you get "open the bleeder for rear left and pump brake pedal". Now you bleed the left driver side as you normally would. Hit next and "open bleeder for front right hit ok when ready". For the right side the software will actually cycle the ABS pump for a few min. So you crack open the bleeder (I use a hose into a bucket on the bleeder) and hit ok. Now you will hear the car's ABS pump makes all kinda of weird rhythmic sounds like its singing too you and some fluid will come out of the hose. This is where I'm not sure I'm doing it correctly. I decided to let the car do its thing, and then bleed that corner as normal figuring if any bubbles came out of the ABS pump there may be air in that caliper now. I was thinking maybe I was supposed to bleed WHILE the car was pumping the ABS? But that makes less sense to me. So after the rhythmic vibrating I bled as normal and hit next. Then you do the same thing for the last screen on the tool, "open bleeder for right rear" and do the ABS pump thing again then bleed after.
I was slightly disapointed my brake pedal was not rock hard like I was expecting (it was moosh before I did this) but then when I actually stopped the car I had so much brake control and feeling while I was braking it was like a new car. Before I got the air out of the system there was a numb dead spot in the middle of the pedal and it was very hard to glide brake up to a stop sign or red light. I'm sure the dealer ABS bleed procedure is in the shop manuals I should probably check if you're supposed to bleed while the ABS pump is pumping fluid thru or after.
