Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, 2004 Chevrolet Cab & Chassis Silverado, and 2003 GMC Sierra. However, it is still accessible from the selected car via links, so may be relevant.

The IPC does not receive a valid health signal from the SBA for 5 consecutive ignition cycles.
The SBA is producing a supplemental brake assist signal indicating a system failure.