U0104: Lost Communication With Cruise Control Module
What to do
Cruise control will not switch on. The car drives entirely normally otherwise, and there is no risk of it accelerating by itself — the engine module simply is not receiving any request.
If this is a car with adaptive cruise control, take a moment to check what else has stopped working. Automatic emergency braking, distance warning and lane assistance often share the same module, so they may be unavailable too — and the dashboard is not always emphatic about it. Assuming an assistance system is still watching when it is not is the risk here, rather than anything the car will do on its own.
What this code means
The cruise control module has stopped being heard from. The general reasoning is at U0100.
On most modern vehicles cruise control is a function of the engine module rather than a box of its own, so this code appears where the system is genuinely separate — commonly on vehicles with adaptive cruise control, where a radar or camera module does the work of deciding what speed to hold.
The failure is safe by design and unremarkable to drive: cruise control simply refuses to engage. The module cannot request a speed, so no speed is requested. There is no scenario in which losing this conversation causes the vehicle to accelerate on its own — the engine module will not act on a request it is not receiving.
Where the system is adaptive, the same fault usually takes automatic emergency braking and distance warning with it, since those share the module. That is worth knowing rather than discovering: driver assistance features that are quietly unavailable are ones people go on relying upon.
Likely causes
Start here
- Corroded or loose connector · easy
- Damaged data bus wiring · moderate
Less common
- Failed power or earth supply to the module · moderate
- Blown fuse or failed supply · easy
- Faulty cruise control module · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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