2004 Chevy Cavalier U1064 and U1301 Code: Loss of Communication with Body Control Module

Does your OBD2 scan tool display codes stored in all vehicle modules? This can help identify if other modules are also reporting faults.

I use an Actron CP9670 code reader, which reads engine-related OBDII codes but does not support communication with body control or other module networks. I tested it on my Chevrolet Avalanche and found no history of stored codes from modules — suggesting limited capability for network diagnostics.

Have you considered performing a circuit continuity test, especially in the A/C fan and gauge control circuits? These may be triggering the communication failure when activated.

I plan to start with the A/C fan and gauge circuits since they trigger the fault codes. My scan tool supports live data monitoring, but I'm unsure what specific parameters to watch for. I’m considering testing the fan without the A/C to see if that eliminates the issue — any suggestions would be greatly appreciated.

U1064 and U1301 are module-to-module communication faults related to Class 2 network signals. Diagnosing these requires a lab-grade oscilloscope and a high-quality scan tool capable of pinging modules on the CAN bus. The issue could stem from a bad body control module, faulty wiring (especially under the dashboard), or improper power/ground connections. A shorted module can cause complete network failure. Without proper diagnostic tools, it's difficult to isolate the root cause. I recommend visiting a specialized diagnostic shop or dealership with access to professional equipment. These U codes are notoriously challenging for DIYers.

Thank you for your detailed input. I don’t have access to advanced diagnostic tools and am hesitant to replace the BCM without confirming the issue — I’d rather avoid damaging a component that may not be faulty. I’ll update this thread once the repair is complete.

You're welcome! Feel free to post an update when you find a solution or have the vehicle repaired.