U0104

Code

HYUNDAI U — Network/User

Lost Communication With Cruise Control Module | ECM-Cruise Control Module Communication

Brand: HYUNDAI

Type: U — Network/User

Views: UK: 25 EN: 22 RU: 53

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Page language: EN

Blown fuse or loss of power to Cruise Control Module
Open, shorted, or high resistance CAN bus wiring between ECM and Cruise Control Module
Poor or corroded connector pin(s) at CCM or ECM
Cruise Control Module internal failure
ECM CAN transceiver fault or ECM software anomaly
Network interference from other modules or damaged termination resistors

Malfunction indicator lamp (MIL) or communication lamp may illuminate
Cruise control inoperative or not available
Stored U0104 and possibly related U-codes
Loss of certain cruise-related functions on dash (e.g., set speed not displayed)
Possible multiple network module communication warnings

Retrieve freeze frame and related codes with a capable scan tool
Check for other communication U-codes on same CAN network
Verify battery voltage is within specification and ignition position correct
Inspect fuse(s) supplying Cruise Control Module and ECM
Visually inspect connectors and wiring at Cruise Control Module and ECM for damage, corrosion, or pushed-out pins
Check CAN high/low wiring for continuity and short to ground or battery

CAN bus messages from Cruise Control Module (module status, set speed, cruise ON/OFF, brake/clutch inputs)
Expected CAN bus voltage idle: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–1.0 V (dominant/recessive states on active bus)
Bus termination resistance ≈ 60 ohms (two 120 ohm terminals in parallel)
Message frequency: regular periodic status messages from CCM (varies by model; should be visible on scan tool/oscilloscope)

Connect OEM-capable scan tool and confirm U0104 and any related codes; note module presence and data stream status
Verify vehicle battery voltage and inspect fuses/power supplies to Cruise Control Module and ECM; replace blown fuses as required
Visually inspect and secure connectors at Cruise Control Module and ECM; repair any damaged terminals or corrosion
Using wiring diagrams, identify CAN wires between ECM and Cruise Control Module. Check continuity and resistance of CAN_H and CAN_L between modules
Measure CAN bus termination resistance with ignition off; if not ≈60 ohms, inspect termination resistors and wiring for opens/shorts
With a lab scope or CAN data logger, monitor CAN_H/CAN_L waveforms and scan-tool data to confirm whether CCM messages are transmitted. Look for dominant/recessive transitions and noise
If no messages from CCM but module has power and ground, inspect CCM grounds and power feeds; if present, suspect CCM internal failure—verify by substituting a known-good module if available or bench testing per OEM procedure
If intermittent, perform wiggle tests and flex wiring harness while monitoring for loss of communication; repair wiring or connectors found to be intermittent
After repairs, clear codes and road-test while monitoring CAN data and cruise function to confirm communication is restored

⚠️ Status

ECM is not receiving CAN messages from the Cruise Control Module. Communication between ECM and Cruise Control Module is lost or unreliable.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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U0104 — Lost Communication With Cruise Control Module | ECM-Cruise Control Module Communication