U0104 – Lost Communication With Cruise Control Module

System: Network | Standard: ISO/SAE Controlled | Fault type: General

Definition source: SAE J2012/J2012DA (industry standard)

DTC U0104 indicates the vehicle detected a network communication problem involving the cruise control module. In plain terms, one or more modules on the vehicle’s communication network expected to exchange messages with the cruise control module, but those messages were not received within the required time or in the expected manner. Because network architecture, module locations, and monitoring logic vary by vehicle, the exact conditions that set U0104 (and what features are disabled as a result) can differ. Always confirm the module naming, network topology, fuse assignments, connector views, and test procedures using the correct service information for the specific vehicle before beginning pinpoint tests.

What Does U0104 Mean?

U0104 means Lost Communication With Cruise Control Module. This is a network-related diagnostic trouble code where a control module (often the powertrain or body controller, depending on vehicle design) determines that communication with the cruise control module has been lost. Per SAE J2012 DTC conventions, a “U” code points to a network communication issue rather than a direct sensor reading out of range. U0104 does not, by itself, prove the cruise control module is faulty; it indicates that expected network messages associated with the cruise control module are missing, invalid, or not acknowledged, and further testing is required to determine whether the cause is power/ground, wiring, the network itself, or a module problem.

Quick Reference

• Subsystem: Vehicle network communication to/from the cruise control module.
• Common triggers: Cruise control module offline, network bus disruption, power/ground interruption to the module, or poor connector contact.
• Likely root-cause buckets: Wiring/connector faults, power/ground supply issues, network (bus) faults, module internal fault, or configuration/software issues (varies by vehicle).
• Severity: Typically disables cruise control functions; may also set warning messages and affect related driver-assist features depending on integration.
• First checks: Verify battery condition, check related fuses/relays, confirm the cruise control module powers up, and scan for additional network codes.
• Common mistakes: Replacing the cruise control module before verifying power/ground integrity and network wiring continuity at the module connector.

Theory of Operation

Modern vehicles use a shared communication network so multiple modules can exchange status and command messages. The cruise control module (or an integrated controller that performs cruise control functions) broadcasts and receives messages such as switch requests, system enable status, fault states, and coordination data with other modules. Other modules monitor these messages to confirm the cruise system is present and communicating.

U0104 sets when a module that expects cruise control-related communications determines they are missing or not plausible for a calibrated period. This loss of communication can occur if the cruise control module loses power or ground, if a connector has high resistance or intermittent contact, if the network wiring is open/shorted, or if network traffic is disrupted. The vehicle may respond by disabling cruise control and logging additional network DTCs that help identify whether the issue is localized to one module or affects the entire bus.

Symptoms

• Cruise inoperative: Cruise control will not set, resume, or maintain speed.
• Warning message: Driver information display may show a cruise control or driver-assist unavailable message (varies by vehicle).
• Indicator behavior: Cruise indicator lamp may not illuminate or may behave unexpectedly when attempting to enable cruise.
• Stored network codes: Additional communication DTCs may be present in other modules, sometimes pointing to a broader network issue.
• Intermittent operation: Cruise may work sometimes and fail other times, especially over bumps or during steering column/under-dash movement (connector sensitivity varies by vehicle).
• Related feature limitations: Functions that share inputs with cruise control (such as certain driver-assist features) may be limited or disabled depending on system design.

Common Causes

• Open, shorted, or high-resistance network wiring between the cruise control module and the rest of the vehicle network
• Poor connector seating, backed-out terminals, pin fit issues, corrosion, or moisture intrusion at network connectors (module-side or harness-side)
• Loss of power feed to the cruise control module (blown fuse, faulty relay, or open in the power supply circuit)
• Loss of module ground (loose ground fastener, ground splice issue, or damaged ground wire)
• Network bus fault affecting multiple modules (short between bus circuits, short to power/ground, or an improperly connected module)
• Intermittent harness damage near common stress points (routing clips, sharp edges, prior repair areas) causing momentary communication dropouts
• Cruise control module internal fault (electronics failure) after power/ground and network integrity are verified
• Configuration, programming, or software mismatch following module replacement or certain repairs (varies by vehicle)

Diagnosis Steps

Tools typically needed include a capable scan tool that can read network DTCs from multiple modules and view module status, a digital multimeter, and access to vehicle-specific wiring diagrams and connector views. A backprobe kit and terminal inspection tools are helpful. If available, a breakout lead or bus diagnostic adapter can make network checks safer and more repeatable.

1. Confirm the complaint and capture a full vehicle scan: Record U0104 and any other network or power-related DTCs. Note which modules report the cruise control module as “not responding” and whether multiple “lost communication” codes are present, which may indicate a broader network issue.
2. Check scan tool module presence: Attempt to communicate directly with the cruise control module. If it does not respond, treat the issue as a power/ground/network integrity problem until proven otherwise. If it does respond, focus on intermittent communication, connector integrity, and network quality.
3. Review freeze frame and module status (if supported): Note when the fault sets (key-on, during driving, after a bump, after a battery event). Use live status indicators such as “module online/offline” or network health screens where available; behavior varies by vehicle.
4. Prioritize power supply checks to the cruise control module: Using service information, identify all module power feeds (battery, ignition, wake-up) and grounds. Verify fuses are correct and intact under load, not just visually. If a fuse is open, do not replace it repeatedly without finding the underlying cause.
5. Perform voltage-drop testing on grounds and feeds: With the module powered and the circuit loaded, check for excessive voltage drop on the module ground path and on the power feed path. High resistance at a splice, fuse connection, or ground point can allow partial operation but still cause communication loss.
6. Inspect connectors and terminals at the cruise control module: Disconnect the module connector(s) and inspect for corrosion, moisture, bent pins, spread terminals, and poor terminal retention. Confirm proper connector locking and strain relief. Repair terminal issues as needed, then recheck communication.
7. Check network wiring integrity end-to-end: Using wiring diagrams, verify continuity of the network circuits from the module connector to the next network junction point. Look for opens, shorts between the network circuits, and shorts to power/ground. Do not pierce insulation unless approved by service procedures.
8. Isolate potential network disruption: If multiple modules show communication issues, inspect network splices and junction connectors. If service information allows, isolate segments by disconnecting modules or junctions one at a time to see whether network communication returns, indicating a shorted segment or a single module pulling the bus down.
9. Wiggle test for intermittents: With live data/logging running (module presence, network DTC counters, or communication status), gently flex the harness and connectors at likely stress points: near the module, through pass-throughs, near brackets, and near splice packs. If the fault toggles, pinpoint the exact area and inspect/repair the harness or terminals.
10. Clear DTCs and validate with a controlled road test: After repairs, clear all related DTCs, cycle the ignition as required, and perform a road test while logging network status. Confirm U0104 does not reset and that cruise control-related functions operate normally. If the module requires setup/programming after any replacement, complete those steps per service information.

Professional tip: When U0104 appears alongside several other “lost communication” codes, avoid targeting the cruise control module first. Prove network integrity and stable power/ground at the affected modules with voltage-drop testing and live network status logging; many repeat comebacks trace to marginal grounds, splice resistance, or a harness intermittently opening under vibration.

Possible Fixes & Repair Costs

Repair costs for U0104 vary widely because the fix depends on where communication is being lost, whether the issue is power/ground, wiring/connectors, or a module-level fault, and how much diagnosis time is needed. Parts, labor rates, and vehicle design differences also affect total cost.

• Restore power/ground to the cruise control module: Verify and repair the module’s power feeds, grounds, and related fuse/relay circuits as required.
• Repair network wiring faults: Fix opens, shorts, or high-resistance conditions in the communication bus wiring between modules (varies by vehicle).
• Connector service: Clean/repair terminals, correct poor pin fit, address corrosion, and ensure connectors are fully seated and properly locked.
• Harness repair: Repair chafed, pinched, or internally broken wiring sections and restore proper routing/strain relief.
• Module replacement (only after testing): Replace the cruise control module only if power/ground and network integrity are proven good and module non-communication is confirmed.
• Configuration/programming: Perform required setup, coding, or relearn procedures after module replacement (procedures vary by vehicle).

Can I Still Drive With U0104?

In many vehicles, U0104 mainly affects cruise control operation, so the vehicle may still be drivable; however, treat it as a network communication fault that can indicate a broader electrical issue. If you also have warning lights, reduced power behavior, stalling, no-start, or brake/steering-related warnings, do not drive and have the vehicle inspected. Even when driveability feels normal, cruise control may be disabled or unreliable, so avoid relying on it until the cause is verified and repaired.

What Happens If You Ignore U0104?

Ignoring U0104 can lead to persistent loss of cruise control functionality and recurring warning indicators, and it may mask an intermittent network, power, or ground problem that worsens over time. If the underlying issue is harness damage or a poor connection, it can become more frequent and potentially begin affecting communication with other modules, increasing the likelihood of additional network-related DTCs and harder-to-diagnose intermittent faults.

Last updated: March 14, 2026

Vehicles Commonly Affected by U0104

• Vehicles with a dedicated cruise control module that communicates over a shared network rather than a standalone system.
• Models with multiple driver-assist features where cruise control functions depend on network messaging between modules.
• Vehicles with steering wheel switch networks that route switch commands through one module to another (design varies by vehicle).
• Platforms with high network traffic where marginal wiring/terminal conditions can cause intermittent communication loss.
• Vehicles with recent electrical repairs involving interior trim removal, steering column work, or harness disturbance.
• Vehicles with known low-voltage events such as weak batteries or charging system concerns that can drop modules offline.
• Vehicles exposed to connector contamination where moisture or debris can affect terminal contact (location varies by vehicle).
• Any vehicle using networked modules where an open/short/high-resistance fault can interrupt communication.

After completing repairs, clear DTCs, confirm the cruise control module is visible on the scan tool, and perform a road test while monitoring network communication status to ensure U0104 does not return.