Antilock Brake System Automated Bleed
Refer to Brake Fluid Irritant Warning .
Refer to Brake Fluid Effects on Paint and Electrical Components Caution .
Before performing the ABS Automated Bleed Procedure, first perform a pressure bleed of the base brake system. Hydraulic Brake System Bleeding (Manual) , or Hydraulic Brake System Bleeding (Pressure) 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 toward the brake corners.
Performing the Automated Bleed Procedure
- Raise and support the vehicle. Lifting and Jacking the Vehicle
- Remove all four tire and wheel assemblies. Tire and Wheel Removal and Installation
- Inspect the brake system for leaks and visual damage. Repair or replace components as needed.
- Lower the vehicle.
- Inspect the battery state of charge.
- Install a scan tool.
- Turn the ignition ON, with the engine OFF.
- If the vehicle is equipped with push button start, place the ignition in Service Only Mode.
- Do not apply the brake pedal.
- Press and hold the ignition mode switch for a minimum of 5 seconds.
- Release the ignition mode switch when the switch indicator illuminates green.
- With the scan tool, establish communications with the ABS system. Select Control Functions. Select Automated Bleed from the Control Functions menu.
- Raise and support the vehicle. Lifting and Jacking the Vehicle
- Following the directions given on the scan tool, pressure bleed the base brake system. Hydraulic Brake System Bleeding (Manual) , or Hydraulic Brake System Bleeding (Pressure)
- Follow the scan tool directions until the desired brake pedal height is achieved.
- If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure:
- If a DTC is detected, refer to Diagnostic Trouble Code (DTC) List - Vehicle , and diagnose the appropriate DTC.
- If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Hydraulic Brake System Bleeding (Manual) , or Hydraulic Brake System Bleeding (Pressure)
- When the desired pedal height is achieved, press the brake pedal to inspect for firmness.
- Lower the vehicle.
- Remove the scan tool.
- If the vehicle is equipped with push button start, remove the vehicle from Service Only Mode.
- Do not apply the brake pedal.
- Press the ignition mode switch once and release.
- The ignition mode switch will no longer be illuminated.
- The vehicle may be started normally.
- Install the tire and wheel assemblies. Tire and Wheel Removal and Installation
- Inspect the brake fluid level. Brake Master Cylinder Reservoir Filling
- Road test the vehicle while inspecting that the pedal remains high and firm.
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.