Code U0155 on the 2021 Lexus RX indicates lost communication with the instrument cluster module. The digital cluster receives and displays data from numerous vehicle systems, and communication loss results in missing or incorrect dashboard information.
Instrument Cluster Integration
The Lexus RX's instrument cluster communicates with the engine, transmission, ABS, and other modules to display speed, RPM, fuel level, warning lights, and messages. The digital cluster is essentially a computer that renders this information graphically. Communication loss means it cannot receive data to display.
Display Effects
With U0155 present, the instrument cluster may go blank, display error messages, or show incorrect/stuck readings. Warning lights may illuminate or fail to illuminate. The odometer may not increment. Navigation arrows and driver assist graphics won't display. The multi-information display becomes unusable.
Diagnostic Approach
The instrument cluster is behind the steering wheel in the dashboard. Check the cluster's electrical connector - these can work loose or develop contact issues. Verify power and ground supplies to the cluster. Test CAN communication at the cluster connector. Recent dashboard work, including airbag service, may have disturbed connections.
Repair Considerations
Many U0155 codes result from connection issues. If the cluster itself has failed, replacement requires Toyota/Lexus Techstream for programming. The new cluster must be configured for the vehicle's options and calibrated for accurate displays.