U0104 — Data bus: cruise control module – no communication #

Note: The exact wording for this trouble code may differ depending on the vehicle manufacturer.

• Data bus: cruise control module – no communication (Generic/OEMs)
• Lost Communication With Cruise Control Module (Ford, GM)
• No Communication With Cruise Control Control Module (Volkswagen, Audi)
• Cruise Control Module Communication Error (Chrysler, FCA)

Summary of code U0104 #

DTC U0104 stands for “Data bus: cruise control module – no communication.” This code is set when a vehicle’s main computer (often called the Powertrain Control Module or PCM) cannot establish contact with the cruise control module via the data bus network. The data bus in modern vehicles is like a digital nervous system, commonly using the CAN (Controller Area Network) protocol to allow different modules to “talk” to each other. When the PCM loses communication with the cruise control module for a certain period, this code is stored. It can affect cruise control operation and sometimes other systems relying on data sharing. Although the vehicle may remain drivable, this code may point to deeper electrical or network issues that should not be ignored.

Common symptoms for code U0104 #

When U0104 appears, symptoms vary depending on how your vehicle is designed and how reliant it is on the cruise control module’s data. Some issues may be subtle, while others can be obvious. You may notice:

• Cruise control system inoperative (cannot engage or maintain speed)
• Cruise control warning light illuminated
• Check Engine Light (CEL) or Service light activated
• Loss of related driver assistance features (such as adaptive cruise, speed limiter, etc.)
• Intermittent or sudden loss of cruise control during driving
• Other unrelated warning lights (sometimes, due to network issues)

Probable causes for code U0104 #

The U0104 code is triggered most often by communication problems between modules, commonly caused by wiring, connector, or module faults. The most frequent causes, in order of likelihood, include:

1. Faulty cruise control module (internal failure or malfunction)
2. Damaged or corroded wiring/connectors on the CAN data lines to the cruise control module
3. Open circuit (broken wire or poor connection) in the data bus wiring
4. Short to ground or power in data bus wiring
5. Faulty PCM or Body Control Module (BCM) (less common, but possible)
6. Aftermarket accessories interfering with CAN network communication
7. Low battery voltage or power supply issue to the cruise control module

Step-by-step diagnosis for code U0104 #

Diagnosing a U0104 code requires a systematic approach, focusing on both the cruise control module and the data bus wiring network. Here’s a proven step-by-step process:

1. Check for other DTCs (especially network-related codes) and record them. Clear codes and see if U0104 returns.
2. Inspect battery voltage and charging system to ensure stable power supply.
3. Visually inspect wiring and connectors at the cruise control module and along the data bus for damage, corrosion, or loose connections.
4. Check fuses related to the cruise control and data bus circuits.
5. Use a scan tool capable of accessing the data bus to verify if the cruise control module responds or appears as “offline.”
6. Check the CAN bus resistance (typically 60 ohms across the network) using a multimeter at the diagnostic connector.
7. Disconnect aftermarket accessories (if present) and retest.
8. Substitute a known-good cruise control module (if available) to isolate a module fault.
9. Consult OEM wiring diagrams and perform continuity checks on data bus wiring if needed.

Possible repairs for code U0104 #

The right repair depends directly on the underlying cause. Once identified, typical solutions for U0104 include:

• Repairing or replacing damaged wiring or corroded connectors
• Replacing the cruise control module if found faulty
• Cleaning and securing connector terminals
• Correcting power/ground faults to the module
• Repairing open or short circuits in the data bus wiring
• Removing or correcting aftermarket device wiring interfering with the data bus
• Replacing the PCM or BCM (only after confirming all other causes are ruled out)

Is it safe to drive with code U0104? #

Limited — While many vehicles remain drivable with a U0104 code, your cruise control system will not function, and in rare cases, other driver-assist features may also be affected. If your daily driving relies heavily on cruise control, this could be a significant inconvenience. More importantly, a persistent communication fault may indicate a growing electrical issue that could spread to other modules, so prompt diagnosis is recommended.

Vehicles most commonly affected by code U0104 #

This code can appear in a wide range of modern vehicles using CAN bus networks and electronic cruise control modules. However, it’s more frequently reported in:

• Ford (F-150, Escape, Fusion, Explorer)
• Chevrolet/GMC (Silverado, Sierra, Malibu, Equinox)
• Volkswagen/Audi (Golf, Passat, Jetta, A3, A4)
• Chrysler/Dodge/Jeep (Ram 1500, Grand Cherokee, Charger)
• Toyota/Lexus (Camry, Corolla, Highlander, RX)
• Honda/Acura (Civic, Accord, CR-V, MDX)

Note: This list is not exhaustive. Any vehicle using electronic cruise control and network communications could potentially set U0104.

Common mistakes and best practices for code U0104 #

Misdiagnosis of U0104 is common due to the complexity of vehicle networks and the temptation to replace modules prematurely. Keep these best practices in mind:

• Do not replace the cruise control module first — Always check wiring, connectors, and power/ground before considering module replacement.
• Check for related codes first — U0104 may be secondary to a more general network or power issue.
• Thoroughly inspect for water intrusion or corrosion around connectors and modules.
• Always clear codes and retest after each step to confirm the fix.
• Use a scan tool with network monitoring to see which modules are “missing” or “offline.”
• Document all steps for future reference and warranty purposes.

Express FAQ for code U0104 #

Here are quick answers to some common questions about code U0104:

• Q: Will replacing the cruise control module fix U0104?
  A: Not always. Wiring, connector, or power issues are common causes. Always diagnose the network first.
• Q: Can a dead battery cause U0104?
  A: Yes. Low voltage or power supply interruptions can temporarily disrupt module communication and trigger this code.
• Q: Is U0104 a common code on older cars?
  A: No. U0104 typically appears on vehicles equipped with electronic cruise control and data bus networking, usually from the mid-2000s onward.

If you have any doubts or the code keeps returning after basic checks, consulting a professional with OEM-level diagnostic equipment is always the safest route.