Code Definition

U1100 — CAN bus Circuit communication with pre-crash seatbelt control module lost

System: Network Communication  |  Type: Manufacturer-Specific  |  Make: Toyota

About U1100

U1100 is a manufacturer-specific network communication diagnostic trouble code recorded for Toyota vehicles. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

When U1100 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

U1100 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

DTC U1100 is a Toyota specific network code set when a monitoring module, typically the airbag or main body ECU, loses CAN bus communication with the precrash seatbelt control module. The precrash seatbelt system tightens the seatbelts when the system anticipates a collision, and its control module reports status to the network at regular intervals. When the monitoring module stops receiving those periodic frames within the expected time window, it stores U1100 and the precrash seatbelt function may be disabled. The driver will usually see a warning light, and related loss of communication or ...

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