Spongy to no brakes and no power steering at idle

FSTONE22

MEMBER
2006 GMC SIERRA
0.6L
V8
4WD
AUTOMATIC
135,000 MILES

Brakes spongy or going to floor. Bled many times with new hydro boost. And master cylinder and calipers, pads, rotors. Also power steering gets hard to nothing at stops. Replaced pump and hydro booster. Not losing fluid.

Thursday, March 21st, 2019 AT 5:11 AM

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

Did you do the automated brake bleed on the ABS system? You may have air in the ABS system and the only way to bleed it is with a scan tool.

Roy

Procedure

ABS Automated Bleed Procedure

Notice: When adding fluid to the brake master cylinder reservoir, use only Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. The use of any type of fluid other than the recommended type of brake fluid, may cause contamination which could result in damage to the internal rubber seals and/or rubber linings of hydraulic brake system components.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Service Precautions.

Important: This procedure may be performed on all vehicles EXCEPT those equipped with option code JL4, Vehicle Stability Enhancement System (VSES).

Important: 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).

1. Install a scan tool to the vehicle.
2. Start the engine and allow the engine to idle.
3. Depress the brake pedal firmly and maintain steady pressure on the pedal.
4. Using the scan tool, begin the automated bleed procedure.
5. Follow the instructions on the scan tool to complete the automated bleed procedure. Release the brake pedal between each test sequence.
6. Turn the ignition OFF.
7. Remove the scan tool from the vehicle.
8. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme II GM P/N 12377967 (Canadian P/N 992667) or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
9. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding (Manual).
10. With the ignition OFF, apply the brakes 3-5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
11. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
12. 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, Brakes > Component Tests and General Diagnostics
13. Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
14. 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, Brakes > Symptom Related Diagnostic Procedures
15. Drive the vehicle to exceed 13 kph (8 mph) to allow ABS initialization to occur. Observe brake pedal feel.
16. If the brake pedal feels spongy, repeat the automated bleeding procedure until a firm brake pedal is obtained.