2007 Silverado brake issues

[BowYoda]

Hello all, 1st time poster.  I really need some help.   My kid at school calls me, says ABS light on and he can't go/ turn his truck BC wheels feel locked up. He says guy came along, did something in fuse box and wheels released.   I trailered truck home.  Installed NEW; rotors, front calipers, pads, rubber lines, master cylinder, and brake booster in my '07 Silverado LT Z71,  5.3L

THE ISSUE...   I have bled 4qts of fluid and can't seem to get rid of air annnnnd the calipers will not release.  They are not locked but still tight enough to burn my rotors up.  I bled in the order Br, Bl, Fr, Fl.    Also, bled at MC & the ABS Mod.

Somebody please send some help... Next starting point, 

still have truck on jack stands 

[Mikebtte]

If you loosen the 2 bolts holding the master cylinder to the brake booster dose the issue get better?

I have seen the adjustable head on the inside need adjusting. sometimes it will hold pressure on the master Cylinder and hold the brakes on.

Not sure what cause them to become out of adjustment, but that little head can be adjusted.

Edited March 27, 2019 by Mikebtte

[swathdiver]

Did you pull the ABS codes that set off this light and if so, what was it?

 

A bi-directional scan tool like the Tech-2 is needed to properly bleed the ABS system.  There's no doing it without one properly.

[BowYoda]

Thanks guys.... Will try these today

[BowYoda]

Ok mike & swathdiver, Im pretty sure I have rod at right length, calipers are releasing.   Thanks!   

Got tech II scanner and did automatic brake bleed twice, then bled the regular way... brakes will still go to floor, like they have air in lines, on 1st push,. But if I pump them 3or 4 quick pumps , it will skid on gravel road.  

Any ideas???   Most mystifying brake job I've ever done.   Btw, I'm not a pro mechanic, just your typical diy guy.

 Any ideas are greatly appreciated!

[swathdiver]

4 hours ago, BowYoda said:

Ok mike & swathdiver, Im pretty sure I have rod at right length, calipers are releasing.   Thanks!   

Got tech II scanner and did automatic brake bleed twice, then bled the regular way... brakes will still go to floor, like they have air in lines, on 1st push,. But if I pump them 3or 4 quick pumps , it will skid on gravel road.  

Any ideas???   Most mystifying brake job I've ever done.   Btw, I'm not a pro mechanic, just your typical diy guy.

 Any ideas are greatly appreciated!

From the shop manual:

 

Antilock Brake System Automated Bleed Procedure 

 

Note: The base hydraulic brake system must be bled before performing this automated bleeding procedure. If you have not yet performed the base hydraulic brake system bleeding procedure, refer to Hydraulic Brake System Bleeding (Manual) (See: Service and Repair)Hydraulic Brake System Bleeding (Pressure) (See: Service and Repair) before proceeding.
 

1. Install a scan tool.
2. Start the engine and allow the engine to idle.
3. Using the scan tool, begin the automated bleed procedure.
4. Follow the instructions on the scan tool to complete the automated bleed procedure. Apply the brake pedal when instructed by the scan tool.
5. Turn the ignition OFF.
6. Remove the scan tool from the vehicle.
7. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
8. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding (Manual) (See: Service and Repair)Hydraulic Brake System Bleeding (Pressure) (See: Service and Repair).
9. With the ignition OFF, apply the brakes several times until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
10. Slowly apply and release the brake pedal. Observe the feel of the brake pedal.
11. If the brake pedal feels spongy, repeat the automated bleeding procedure. If the brake pedal still feels spongy after repeating the automated bleeding procedure, inspect the brake system for external leaks. Refer to Brake System External Leak Inspection (See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics).
12. Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
13. If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired. Refer to Symptoms - Hydraulic Brakes (See: Hydraulic System\Testing and Inspection\Symptom Related Diagnostic Procedures\Symptoms - Hydraulic Brakes).
14. Drive the vehicle to exceed 13 km/h (8 mph) to allow ABS initialization to occur. Observe the feel of the brake pedal.
15. If the brake pedal feels spongy, repeat the automated bleeding procedure until a firm brake pedal is obtained.

[swathdiver]

You have to do the regular bleed first.  From the shop manual:

 

Hydraulic Brake System Bleeding (Manual) 
Warning: Refer to Brake Fluid Irritant Warning (See: Service Precautions\Technician Safety Information\Brake Fluid Irritant Warning). 

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution (See: Service Precautions\Vehicle Damage Warnings\Brake Fluid Effects on Paint and Electrical Components Caution).
 

1. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
2. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.
3. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, you must perform the following steps:

1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If necessary add GM approved brake fluid from a clean, sealed brake fluid container. Refer to Fluid and Lubricant Recommendations (See: Maintenance\Specifications). If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
2. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe from the front port of the brake master cylinder.
3. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
4. Reconnect the brake pipe to the master cylinder port and tighten securely.
5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
6. Loosen the same brake pipe to purge air from the open port of the master cylinder.
7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
8. Wait 15 seconds, then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
9. With the front brake pipe installed securely to the master cylinder, after all air has been purged from the front port of the master cylinder, loosen and separate the rear brake pipe from the master cylinder, then repeat steps 3.3-3.8.
10. After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.

4. Fill the brake master cylinder reservoir with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Master Cylinder Reservoir Filling (See: Hydraulic System\Brake Master Cylinder\Service and Repair\Procedures\Master Cylinder Reservoir Filling). Ensure that the brake master cylinder reservoir remains at least half-full during this bleeding procedure. Add fluid as needed to maintain the proper level. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
5. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
6. Install a transparent hose over the end of the bleeder valve.
7. Submerge the open end of the transparent hose into a transparent container partially filled with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Fluid and Lubricant Recommendations (See: Maintenance\Specifications).
8. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
9. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
10. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
11. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the same wheel hydraulic circuit.
12. With the right rear wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the right rear hydraulic circuit install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve.
13. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
14. With the left rear wheel hydraulic circuit bleeder valve tightened securely, after all air purged from the left rear hydraulic circuit, install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve.
15. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
16. With the right front wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the right front hydraulic circuit, install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve.
17. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
18. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
19. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Master Cylinder Reservoir Filling (See: Hydraulic System\Brake Master Cylinder\Service and Repair\Procedures\Master Cylinder Reservoir Filling).
20. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
21. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still feels spongy after repeating the bleeding procedure, perform the following steps:

1. Inspect the brake system for external leaks. Refer to Brake System External Leak Inspection (See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics).
2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.

22. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.

Note: If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired.
 

23. If the brake system warning lamp remains illuminated, refer to Symptoms - Hydraulic Brakes (See: Hydraulic System\Testing and Inspection\Symptom Related Diagnostic Procedures\Symptoms - Hydraulic Brakes).

[BowYoda]

Thank you for that page , going to try it again!

question????   Would a bad ABS Modulator cause spongy brakes?   No warning lights are on and scanner is not detecting error codes...

thanks again for all your input!

[swathdiver]

On 4/2/2019 at 1:39 PM, BowYoda said:

Thank you for that page , going to try it again!

question????   Would a bad ABS Modulator cause spongy brakes?   No warning lights are on and scanner is not detecting error codes...

thanks again for all your input!

I don't think so.  It would mean the bleed needs to be done again usually.

[Marcus2]

Not sure if you've solved this problem since it was dated 3/27, but make sure you have installed your new calipers with the bleed screw at the top of the caliper. if it's at the bottom, air can't escape when you bleed them. (Gravity Works ) 

[turnerway14]

On 5/20/2019 at 10:05 PM, Marcus2 said:

Not sure if you've solved this problem since it was dated 3/27, but make sure you have installed your new calipers with the bleed screw at the top of the caliper. if it's at the bottom, air can't escape when you bleed them. (Gravity Works ) 

Dude i was about to lose my grits trying to figure out why i still had air in lines.. sure enough the calipers and brackets were backwards. Funny thing is i double checked the part numbers before throwing it back together LOL. You saved the day though man, and i learned a forever life lesson! THANK YOU!