Pre-charge Bleed
The Pre-charge bleed procedure is to be performed when air may have been introduced into the precharge pump inlet hose, the precharge pump or the combination valve. Perform the procedure as follows.
IMPORTANT:
If the brake system warning lamp is illuminated, DO NOT allow the vehicle to be driven until the concern is diagnosed and repaired. Refer to Symptoms - Hydraulic Brakes
in Hydraulic Brakes.
- Ensure that the master cylinder reservoir is filled to at least the minimum-fill level with Delco Supreme 11, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT 3 brake fluid from a clean, sealed container.
- Ensure the master cylinder reservoir cap is ON securely.
- Install a scan tool.
- Turn ON the ignition.
- Select the VSES Special Functions menu on the scan tool.
- Select Pre-charge Bleed.
- Press the On key. The precharge pump runs for approximately 3 seconds, circulating fluid from the master cylinder fluid reservoir, through the precharge pump and combination valve, then back to the master cylinder.
- Evaluate the feel of the brake pedal. If the pedal feels spongy, perform a base brake system bleed. Refer to Hydraulic Brake System Bleeding (Manual) or Hydraulic Brake System Bleeding (Pressure) in Hydraulic Brakes.
- Ensure that the master cylinder reservoir is filled to at least the minimum-fill level with Delco Supreme 11, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT 3 brake fluid from a clean, sealed container.