What it means
A control module has stopped receiving expected messages from the park brake control module. Electronic parking brake functions may be limited or unavailable.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The park brake control module manages the electronic parking brake and reports its status to other modules. Those modules expect messages over the vehicle network. U0128 sets when a control module stops receiving messages from the park brake module, which can make electronic parking brake operation or status reporting unavailable.
Common causes
Most likely first.
- Park brake control module power or ground fault
- Damaged network wiring or connector
- Park brake control module failure
- Low system voltage
Symptoms
- Parking brake warning or message
- Electronic parking brake functions may be unavailable
- Other communication codes
How to diagnose it
- Scan all modules and record freeze-frame data and related parking-brake, network, and low-voltage codes before clearing them.
- Check battery condition and charging-system voltage, as low voltage can prevent the park brake module from communicating or operating.
- Inspect the park brake module’s connectors, power and ground wiring, and network harness for corrosion, looseness, or damage.
- Use a scan tool to check whether the park brake module responds and whether the parking brake status is reported consistently.
- If the module has correct power and ground but remains offline, test its network circuits against the vehicle wiring diagram and manufacturer’s specification.
Common fixes
- Correct a weak battery or charging-system fault.
- Clean and secure a loose or corroded park brake module connector.
- Repair damaged network wiring or connector terminals.
- Restore the module’s power or ground supply.
- Replace the park brake control module if its circuits are sound but it remains offline.
Can I keep driving?
Do not assume the electronic parking brake will apply or release reliably; park on level ground and secure the vehicle as directed in its owner’s manual. If the brake is stuck, a brake warning appears, or normal braking changes, stop safely and arrange assistance.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.