U015D: Lost Communication With Automated Driving System Control Module B

What it means

Lost Communication With Automated Driving System Control Module B: the control module has detected this fault condition.

At a glance

• Usually lights the warning light of the system that lost communication
• The engine or gearbox may go into limp mode

How it works

Automated Driving System Control Module B handles a separate part of the vehicle's automated-driving control functions and exchanges status and commands over the network. U015D sets when the reporting module does not receive expected messages from module B for the required time, making features dependent on that module unavailable or limited.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

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 for U015D and related communication codes, and review freeze-frame data for low voltage or a wider network fault.
2. Check battery condition and charging-system operation before tracing module B, since low voltage can interrupt communication.
3. Inspect Automated Driving System Control Module B's power, ground, fuses, network connectors, and wiring for damage or corrosion.
4. Use a scan tool to check whether module B responds and identify which automated-driving functions are unavailable.
5. If power and ground are correct, test the CAN wiring and gateway communication path for opens, shorts, or routing faults.
6. If the network path is intact, investigate module B and any termination issue using the manufacturer's diagnostic information.

Common fixes

• Restore battery charge or repair a charging-system fault.
• Repair a blown fuse or poor power or ground connection to module B.
• Repair damaged network wiring or connector terminals, or correct a verified gateway routing fault.
• Repair a confirmed termination fault to the manufacturer's specification.
• Repair or replace Automated Driving System Control Module B if its supplies and network path are sound.

Can I keep driving?

Do not rely on automated-driving or driver-assistance features while this fault is present; drive yourself and be ready to control the vehicle at all times. Stop safely if a warning indicates the vehicle cannot be controlled safely.