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DTC codes / U05xx · Network communication / U054B

U054BInvalid Data Received From Interior Lighting Control Module A

U054B is a communication fault indicating that a control module on the vehicle's network received invalid or corrupted data from the interior lighting control module designated as 'A'. The module monitoring the network expected a valid data message from the lighting module but instead saw missing, out-of-range, or implausible information, so it flagged the signal as invalid rather than simply absent.

SystemNetwork
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • The check engine light or a body control warning light illuminates on the dashboard.
  • Interior lights may behave erratically, stay on continuously, fail to turn on, or not respond to door or switch inputs.
  • Courtesy lamps, dome lights, or footwell lighting may flicker or operate intermittently.
  • Often no symptoms besides the warning light, especially if the invalid data affects only non-critical lighting functions.
  • Other body electrical features that share the same network segment may act up, such as power windows or remote keyless entry.
  • The vehicle may show a message on the driver information display indicating a lighting system fault or network communication problem.

Common causes, most likely first

  1. A failing interior lighting control module that is producing corrupted or out-of-range data messages.
  2. Damaged or corroded wiring and connectors between the interior lighting module and the network bus, causing signal degradation.
  3. Low battery voltage or a weak charging system that causes modules to reboot or transmit invalid data during voltage sags.
  4. A network bus fault such as a short to ground or a broken wire on the communication line serving the lighting module.
  5. Water intrusion into the interior lighting module or its connectors, leading to internal corrosion and erratic data output.
  6. A software or calibration issue in the interior lighting module that requires a reflash or update.
  7. A faulty ground connection for the interior lighting module, causing reference voltage instability and invalid message content.

How to diagnose and fix it

  1. Perform a full scan of all modules to record stored, pending, and history codes, then clear codes and verify whether U054B returns immediately.
  2. Check battery voltage and charging system output, including a load test, because low voltage is a common cause of invalid data messages.
  3. Inspect the interior lighting control module connectors and harness for corrosion, water intrusion, loose pins, and chafed wires.
  4. Measure resistance and voltage on the network bus wires at the lighting module connector and compare with the manufacturer's specifications.
  5. Substitute a known-good interior lighting control module of the same part number, or perform a module swap test if the vehicle supports it, to see if the invalid data code disappears.
  6. Check and clean the module's ground connection, then retest the network for invalid data messages.
  7. If hardware and wiring check out, reprogram or update the interior lighting control module software per the manufacturer's service procedure.

What invalid data really means here

  • U054B is not a 'no communication' code; the module is talking, but the receiving module rejects the content as implausible, so a simple continuity check on the bus wires may pass while the fault remains.
  • A weak or failing battery is a frequent hidden cause because voltage dips during cranking can make the lighting module transmit corrupted frames that trigger invalid data codes without any hard wiring fault.
  • Technicians often replace the interior lighting module only to find the real problem is a corroded ground or a water leak that damaged the connector, so always inspect for moisture before condemning the module.
  • This code can be set by another module on the same bus that is disrupting communication, so check for other U-codes and network faults before focusing solely on the lighting module.
  • After repairing the root cause, the code may remain stored in multiple modules until each one is cleared, so a full-system code clear is required to confirm the fix.

Can I keep driving with U054B?

The vehicle is generally safe to drive because interior lighting is not a safety-critical system, but avoid driving at night if the interior lights fail in a way that reduces dashboard visibility, and address the fault promptly to prevent network issues from spreading.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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