The U0104 code, Lost Communication with Cruise Control Module (CCM)” is a diagnostic trouble code (DTC) that signals an issue within the communication line between the vehicle’s main control unit (often the ECM or PCM) and the steering effort control module.
This module plays a critical role in vehicles, especially those with power steering assistance, by adjusting the steering effort based on speed, steering wheel position, and other factors. Let’s break down this code, integrating insights from the service cases provided:
U0104 quick overview
| Meaning | U0104: Lost Communication with Cruise Control Module (CCM) |
| Is it serious? | Yes, it can lead to a loss of power steering assistance, making steering more difficult and potentially compromising vehicle safety. |
| Possible causes | – Faulty or damaged wiring harness – Loose, corroded, or damaged connectors – Faults within the Cruise Control module itself – Software needing updates |
| How to diagnose? | Inspect the wiring harness for damage, wear, or signs of corrosion, especially near the steering column and module connectors. Check connectors for looseness, damage, or corrosion at both the steering column and the power steering control module. Perform a software update on the power steering control module if updates are available. Test the steering angle sensor and its connections for integrity and proper operation. |
U0104 Meaning
When your car shows a U0104 code, it’s telling you that it’s having trouble talking to the part of the car that is controlling the cruise control. This can happen if wires get damaged, connections get loose or dirty, or if there’s a problem inside the steering control part itself. It’s like when your phone loses signal; suddenly, you can’t communicate. For your car, this means steering might feel harder, especially at lower speeds or when trying to park. Mechanics will look closely at all the wires and connections, make sure the software is up to date, and check that everything is working as it should to fix this problem.
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How to fix U0104 – learn from mechanics
I looked into U0104 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Land Rover
Vehicle information 2006 Land Rover LR3 4.0L
Issue + repair history
- Occasional lighting of every warning light on the instrument panel, activation of hazard flashers, and lowering of suspension.
- Message center displays transmission fault and “FOLLOW ME HOME LIGHTS ON”.
- Occurs intermittently, often while idling in Park.
- No previous repair history provided except for the replacement of the brake light switch and oil pressure switch, which did not resolve the issue.
Other OBD2 Codes + Test Results
- P0504 – Brake Switch A/B Correlation
- P2605 – Intake Air Heater B Circuit / Open
- U0102 – Lost Communication With Park Brake Control Module
- U0104 – Lost Communication With Steering Effort Control Module
- U0128 – Lost Communication With Restraints Occupant Sensing Control Module
- U0155 – Lost Communication With Headlamp Leveling Control Module
Mechanic suggestions
- Check for voltage loss at idle, inspect battery and alternator conditions.
- Inspect wiring harness for corrosion, especially in areas prone to water ingress like under the left rear wheel well and front left wheel well.
- Verify correct brake bulbs are installed and inspect bulb sockets for proper contact.
- Check for updated software for transmission module.
Final fix
- No final fix identified. Despite various diagnostic efforts, including inspecting wiring harnesses and replacing brake bulbs, the root cause of the issue remains unresolved. The intermittent nature of the problem and complexity of the vehicle’s systems posed challenges in diagnosis and repair efforts.
Case #2: Toyota
Vehicle information 2015 Toyota Camry Hybrid 2.5L
Issue + repair history
- Occasional loss of communication with the Steering Effort Control Module (U0104).
- Occurs intermittently, leading to sporadic power steering assistance.
- No previous repair history provided.
Other OBD2 Codes + Test Results
- U0104 – Lost Communication With Steering Effort Control Module
- No other codes reported.
- Live data shows intermittent signal loss from the steering angle sensor.
Mechanic suggestions
- Inspect wiring harness connections to the Steering Effort Control Module for corrosion or damage.
- Check for loose or damaged connectors at the steering column.
- Perform a software update for the power steering control module.
- Test the integrity of the steering angle sensor and its connection.
Final fix
- Upon inspection, a loose connector at the steering column was discovered. Reconnecting the connector securely resolved the intermittent communication loss with the Steering Effort Control Module. The power steering system now operates normally without any further issues.
Case #3: Honda
Vehicle information 2018 Honda CR-V 1.5L Turbo
Issue + repair history
- Intermittent loss of communication with the Steering Effort Control Module (U0104).
- Occurs sporadically, leading to temporary loss of power steering assistance.
- No previous repair history provided.
Other OBD2 Codes + Test Results
- U0104 – Lost Communication With Steering Effort Control Module
- No other codes detected.
- Live data shows occasional signal interruption from the power steering control module.
Mechanic suggestions
- Inspect the wiring harness for signs of damage or wear, particularly near the steering column.
- Check for loose or corroded connectors at the power steering control module.
- Perform a diagnostic scan to ensure all other modules are communicating properly.
- Conduct a visual inspection of the steering angle sensor and its wiring for any anomalies.
Final fix
- After thorough inspection, a damaged wire in the wiring harness near the steering column was found. Repairing the damaged wire and securing the connections resolved the intermittent loss of communication with the Steering Effort Control Module. The power steering system now functions correctly without any further interruptions.
How to diagnose U0104
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
Based on the service cases from Land Rover, Toyota, and Honda, we see a pattern in diagnosing and addressing U0104:
| Diagnostic Step | Brief Explanation |
|---|---|
| Wiring harness inspection | Check the entire length of the wiring harness for physical damage, wear, and corrosion. |
| Connector check | Ensure all connectors, especially at the steering column and module, are secure and free from corrosion. |
| Software update | If applicable, update the power steering control module’s software to ensure optimal performance. |
| Steering angle sensor test | Verify the integrity and proper function of the steering angle sensor, as it’s crucial for module communication. |
The U0104 code emphasizes the importance of maintaining the vehicle’s electrical and communication systems for safety and performance. Given the potential complexity and safety implications of steering-related issues, seeking professional assistance is often the best course of action for drivers experiencing this code.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko