Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW
Antilock Brake System Automated Bleed
Warning: Refer to Brake Fluid Irritant Warning Brake Fluid Irritant Warning.
Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution Brake Fluid Effects on Paint and Electrical Components Caution.
Note:
* Before performing the ABS Automated Bleed Procedure, first perform a manual or pressure bleed of the base hydraulic brake system. Refer to Hydraulic Brake System Bleeding .
* The automated bleed procedure must be performed when a new brake pressure modulator valve (BPMV) is installed, because the secondary circuits of the new BPMV are not prefilled with brake fluid.
* The automated bleed procedure is recommended when one of the following conditions exist:
- Base brake system bleeding does not achieve the desired pedal height or feel
- Extreme loss of brake fluid has occurred
- Air ingestion is suspected in the secondary circuits of the brake modulator assembly
The ABS Automated Bleed Procedure uses a scan tool to cycle the system solenoid valves and run the pump in order to purge any air from the secondary circuits. These circuits are normally closed off, and are only opened during system initialization at vehicle start up and during ABS operation. The automated bleed procedure opens these secondary circuits and allows any air trapped in these circuits to flow out away from the brake modulator assembly, which is then forced out at the brake corners by the pressure bleeder.
Automated Bleed Procedure
Caution: The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.
1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle Service and Repair.
2. Remove the tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation Service and Repair.
3. Inspect the brake system for leaks and visual damage. Refer to Symptoms - Hydraulic Brakes Symptoms - Hydraulic Brakes. Repair or replace components as needed.
4. Lower the vehicle.
5. Prepare the brake bleeding equipment and the vehicle for a pressure bleed of the base hydraulic brake system. Refer to Hydraulic Brake System Bleeding .
6. Inspect the battery state of charge. Refer to Battery Inspection/Test Battery Inspection/Test.
7. Install a scan tool.
8. Turn the ignition ON, with the engine OFF.
9. With the scan tool, perform the following steps:
1. Select Diagnostics
2. Select the appropriate vehicle information
3. Select Chassis
4. Select Electronic Brake Control Module (EBCM)
5. Select Special Functions
6. Select Automated Bleed
10. With an assistant ready, raise and support the vehicle. Refer to Lifting and Jacking the Vehicle Service and Repair.
Note:
* Apply the brake pedal when instructed, using moderate effort.
* Ensure the pedal remains applied until instructed to release by the scan tool.
* Do not exceed the time period allowed by the scan tool for having the bleeder valves open.
* The bleed sequence for each corner is as follows:
- Left front
- Right front
- Right rear
- Left rear
11. Perform the automated bleed procedure as instructed by the scan tool.
12. If the automated bleed procedure is aborted, a malfunction exists. If a DTC is detected, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle to diagnose the DTC.
13. After completion of the automated bleed procedure, press and hold the brake pedal to inspect for pedal firmness.
14. If the brake pedal feels spongy, repeat the bleed procedure completely.
15. Remove the scan tool.
16. Install the tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation Service and Repair.
17. Lower the vehicle.
18. Adjust the brake fluid level. Refer to Master Cylinder Reservoir Filling Master Cylinder Reservoir Filling.
19. Road test the vehicle while confirming the brake pedal remains high and firm.