U1064 is a manufacturer-specific network code, most commonly associated with General Motors vehicles using the Class 2 serial data network. It indicates a monitoring module has lost communication with the Body Control Module or Device Control Module.
Because it is a network communication fault, the exact application and affected module must be verified before diagnosis. This code identifies a communication failure but does not automatically prove the target module has failed.
Quick Navigation
Key Takeaways
- U1064 indicates a loss of communication with a specific control module, often the BCM or DCM, on a vehicle’s data network.
- Possible causes include open or shorted network wiring, poor electrical connections, or a faulty control module.
- Diagnosis requires verifying network communication, checking module power and ground circuits, and inspecting the data bus.
- Repairs depend on the confirmed root cause and may involve wiring repair or module replacement.
U1064 Code Description and Implications
U1064 is a manufacturer-specific diagnostic trouble code. It is heavily associated with General Motors vehicles equipped with the Class 2 serial data network.
On these GM applications, U1064 indicates that other modules on the network are no longer receiving the expected state of health messages from the Body Control Module or Device Control Module.
When this communication is lost, the affected module cannot share critical data regarding vehicle status, security, or accessory controls with the rest of the network.
Common Causes of the U1064 Code
Possible causes include damaged, open, or shorted wiring in the Class 2 serial data circuit connecting to the affected control module.
A loss of power or a poor ground connection at the module connector can prevent it from powering up and communicating on the network.
An internal failure of the Body Control Module or Device Control Module itself can also cause it to stop transmitting data on the bus.
In some cases, a network-wide communication fault or a failing gateway module may trigger this code alongside other U-codes.
Symptoms Associated With U1064
Symptoms depend heavily on the specific module that has lost communication on the vehicle network.
If the Body Control Module is offline, drivers may experience issues with power accessories, interior lighting, security system functions, or dashboard warning indicators.
The Service Vehicle Soon light may illuminate, and a scan tool will be unable to communicate with the affected module.
MIL behavior varies by application. Some vehicles may illuminate a specific warning light, while others may store the DTC without commanding a primary engine warning lamp.
Diagnosing the U1064 Trouble Code
Diagnosis must begin by confirming the exact factory definition and network topology for the specific make and model.
Retrieve the code and record any related error codes using a scan tool capable of accessing the serial data network.
Inspect the wiring harness and connectors at the affected module for physical damage, corrosion, or loose pins.
Verify that the module is receiving proper battery voltage and ground. If power and ground are present but the module cannot communicate, the module may be internally faulty.
Repairing the U1064 Issue
Repairs must follow the confirmed root cause identified during electrical and network testing.
If the data circuit wiring is open or shorted, repair the affected harness section and secure it away from sharp edges.
If the module lacks power or ground, repair the specific supply circuit or clean the corroded connector terminals.
If the wiring and power supplies test correctly but the module remains offline, follow the manufacturer procedure to replace and program the confirmed failed module.
Cost Considerations for U1064 Repairs
Repair costs for U1064 vary based on the underlying fault, vehicle accessibility, and local labor rates.
Repairing damaged network wiring involves minimal parts costs and moderate labor time depending on harness routing.
Replacing and programming a Body Control Module involves higher parts costs and requires specialized security access and calibration procedures.
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Prevention Strategies for Future Occurrences
Inspecting exposed wiring harnesses under the dashboard and near the kick panels can help prevent chafed wires that lead to network communication faults.
Keeping the interior cabin dry and avoiding liquid spills near the center console may reduce the risk of moisture intrusion into module connectors.
Troubleshooting Tips and Best Practices
Do not assume a U1064 code requires replacing the Body Control Module immediately; a broken wire or poor ground is a highly likely culprit.
Always check for other U-codes in the system. If multiple modules are losing communication, the fault may lie in a central network splice or shared power supply.
Check for applicable technical service bulletins, as manufacturers occasionally release updated wiring harness pigtails or revised module software to address chronic communication dropouts.
More OBD-II Codes
| U1000 | U0100 | U0101 | U0140 |
| U0155 | U1041 | U1017 | U1900 |
| P0600 | P0601 | P0602 | P0603 |
| P0604 | P0605 | P0606 | P0607 |
| P1600 | P1602 | P1603 | P1604 |
| P1605 | P1606 | P1607 | P1608 |
Frequently Asked Questions
Is U1064 a generic or manufacturer-specific code?
No. U1064 is a manufacturer-specific network code. It is most commonly associated with General Motors vehicles and their Class 2 serial data network architecture.
Can a U1064 code cause my car not to start?
Yes. If the lost communication involves a module tied to the vehicle’s anti-theft or security system, the engine immobilizer may activate, resulting in a no-start condition.
Will U1064 clear itself if I fix a wiring issue?
Not automatically. While repairing a broken wire may resolve the underlying cause, the stored code usually requires a scan tool to clear before the monitor can reset.
Is it safe to drive with the U1064 code active?
Driving is conditional. While the engine may run, the loss of the BCM can disable power accessories, lighting, or security features, making prompt repair essential.
Does U1064 mean my BCM is broken?
No. U1064 identifies a communication failure. While the BCM can fail internally, broken network wires, blown fuses, or poor grounds must be ruled out through testing.
What Should You Do About the U1064 Code?
Confirm the exact factory definition and network topology for your specific vehicle application.
Follow the applicable manufacturer diagnostic procedure to test the relevant serial data circuits, power supplies, and the affected control module itself.
Repair or replace the confirmed failed component, then retest the system to ensure the vehicle network operates correctly.
