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GM U1000 Code – Class 2 Communication Lost
No
Safe to drive :
GM vehicles only
Applies only to :
Not applicable to :
This explanation does NOT apply to Chevrolet, Cadillac, Buick, or other brands.
High
Severity level :
When Does This Code Appear on the Vehicles
GM U1000 occurs when Class 2 serial data communication between modules is lost.
What This Code means on the Vehicles
Indicates BCM and ECM are unable to communicate over Class 2 network.
Why This is different from a generic OBD2 Code
Generic OBD-II scanners cannot detect U1000 communication faults.
Common Situations That Trigger This Code
BCM failure; Wiring harness issues; Aftermarket module interference.
What Will NOT Fix This Code
Replacing unrelated sensors; Clearing code without fixing communication.
How to Clear This Code on Vehicles
Diagnose wiring, BCM/ECM modules, use Tech2 or OEM tool to clear.
Related Manufacturer Specific Codes
GM U1010; GM U1040
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