2006 Chevrolet Equinox P1626 Fault: Theft Deterrent Fuel Enable Signal Lost with U2105 and U0100 Codes
I'm experiencing multiple diagnostic trouble codes on my 2006 Chevrolet Equinox, including: - P1626: Theft Deterrent Fuel Enable Signal Lost - C0276: Chassis / SAE / Injector Fault #76 - U2105: Loss of Communication with ECM - U0100: Loss of Communication with TCM All codes appear simultaneously. I'm looking for insight into how these faults are related and whether they point to a specific issue, such as BCM or PCM communication failure. Any experience with this combination on the 2006 Equinox? Is P1626 typically linked to theft deterrent system malfunctions or could it be part of a broader communication problem?
Here's what I found after troubleshooting: P1626: The Vehicle Theft Deterrent System (VTD) is integrated into the Body Control Module (BCM). The Powertrain Control Module (PCM) monitors the State of Health (SOH) serial data message from the VTD to confirm proper communication between the PCM and BCM. If the PCM detects a loss of this SOH signal while the engine is running, DTC P1626 will be set. Importantly, the engine can still start and run if the condition occurs after the PCM has already received a valid theft deterrent password from the BCM and allowed fuel during ignition. U2105: When the ECM loses communication, the SOH message—normally sent every 2 seconds—is no longer transmitted. The receiving module detects this absence and sets DTC U2105. U0100: Similarly, when TCM communication is lost, the SOH signal stops being sent. The receiving module detects the missing message and triggers DTC U0100. These codes often point to a shared root cause—such as BCM-ECM or BCM-TCM communication issues—especially in older 2006 Equinox models with integrated theft deterrent systems.