U02BC: Lost Communication With Localization and Mapping Module

What it means

The vehicle bus reports loss of communication with the localization and mapping module (HD map / SLAM ECU for ADAS and autonomous functions). Lane-level localization and map-based predictions are unavailable.

How it works

The localization and mapping module combines vehicle position inputs with map data to provide lane-level location and map-based predictions to driver-assistance systems. The network monitors messages from this module and sets this code when they stop arriving or cannot be understood. Features that depend on its location or map information may be limited or disabled.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules and save event data to determine when the localization and mapping module went offline and which driver-assistance functions reported related faults.
2. Check live data and the vehicle display for module status, position availability and any messages that identify a lost input or network connection.
3. Inspect the module's connectors and accessible bus wiring for looseness, corrosion, water entry or damage, including any recent collision or repair area.
4. Check the module's specified power and ground using the manufacturer's service information.
5. Test the communication circuit and relevant network connections for opens, shorts or poor contact using the manufacturer's procedure.
6. If power, ground and network checks pass, use the manufacturer's diagnostics to assess the module and confirm that localization data returns after repair.

Common fixes

• Reconnect or repair a loose or corroded connector at the localization and mapping module.
• Repair an open, short or damaged network wire serving the module.
• Restore the module's specified power or ground connection.
• Replace or reprogram the module only if the manufacturer's diagnostic checks confirm a module fault.

Can I keep driving?

You can usually drive, but do not rely on lane-level or map-based assistance that may have been disabled. Pay attention to signs, lane markings and the road, since those features may not account for the vehicle's precise position.