What it means
A control module has lost communication with the cruise control module. Cruise-control functions may be unavailable, depending on the vehicle.
How it works
The cruise control module manages cruise-control functions on vehicles with a dedicated module. It exchanges operating information with other control modules over the vehicle network. U0104 sets when a reporting module stops receiving expected messages from the cruise control module.
Common causes
Most likely first.
- Loss of module power or ground
- Open, shorted, or damaged communication wiring or connector
- Module or gateway fault
Symptoms
- Cruise control may be unavailable
- Warning lights or messages
- Communication faults in other modules
How to diagnose it
- Scan all modules for U0104 and related network codes, saving freeze-frame information to determine when communication was lost.
- Check whether cruise control is unavailable and note any dashboard messages or other functions that failed at the same time.
- Inspect the cruise control module connector and harness for loose connections, corrosion, moisture, or visible damage.
- Check the module's power and ground circuits against the manufacturer's specification, including any conditions captured in the freeze frame.
- Test the communication wiring to the cruise control module for opens, shorts, or poor connections using the vehicle wiring information.
- If power, ground, and network wiring are sound, investigate gateway or module faults using vehicle-specific diagnostics.
Common fixes
- Secure or clean a loose or corroded cruise control module connector.
- Repair damaged network wiring or the module's ground connection.
- Restore the module's power supply and fix the cause of a failed fuse.
- Repair a gateway fault if network testing identifies one.
- Replace or program the cruise control module only after its circuits and network path pass testing.
Can I keep driving?
Ordinary driving is generally possible if the vehicle responds normally to the accelerator and brakes, but do not rely on cruise control. If other warnings or control problems appear, stop safely and have the fault diagnosed.
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.