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GM U1101 Code – BCM to TCM Communication Fault
Limited
Safe to drive :
GM vehicles only
Applies only to :
Not applicable to :
This explanation does NOT apply to other manufacturers.
Medium
Severity level :
When Does This Code Appear on the Vehicles
GM U1101 appears when BCM fails to acknowledge TCM commands.
What This Code means on the Vehicles
Communication failure between BCM and TCM modules.
Why This is different from a generic OBD2 Code
Standard scanners cannot report BCM–TCM-specific codes.
Common Situations That Trigger This Code
Wiring harness damage; BCM failure; TCM firmware mismatch.
What Will NOT Fix This Code
Clearing codes without repairing communication lines.
How to Clear This Code on Vehicles
Inspect wiring, BCM, TCM; clear via Tech2/OEM tool.
Related Manufacturer Specific Codes
GM U1100; GM U1102
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