2001 Monte Carlo SS Fault Codes B0041, B2964, B3128, U1305, U1016: Causes and Fixes for Starting Issues

Have you recently purchased or modified this vehicle? Additional history would be helpful. B0041 relates to airbag system faults — not something a DIYer should attempt without proper training. The presence of multiple codes suggests possible electrical modifications or non-OEM components installed in the system. B2964 points to security system issues, while B3128 indicates a problem with the Body Control Module (BCM) and door lock functions. U-series codes reflect communication failures between vehicle modules — this strongly implies that aftermarket or non-OEM parts may be interfering with the original wiring architecture. A bi-directional scanner like TechII, along with access to ALLDATA or GM service documentation, is required to fully diagnose and resolve these issues.

The vehicle occasionally fails to start, with the security light on but fuel pump operation intact. After replacing the passlock sensor and ignition switch, it functioned normally for two months before recurring last night. The issue appears intermittent, suggesting a weak or unstable signal from the ignition system to the BCM. We replaced the BCM several years ago, yet symptoms persist. This points toward potential wiring degradation or communication failure between the ignition module and BCM — possibly due to aging components or poor grounding. All parts are OEM, with no modifications. The diagnostic codes (B0041, B2964, B3128, U1305, U1016) were pulled using an OBD2 scanner, but I need guidance on interpreting them and identifying the root cause.

No wires have been cut or modified. All components are original equipment manufacturer (OEM), including the ignition system, BCM, and wiring harnesses. This rules out major electrical alterations as a source of the fault codes.