Code
C1611
HYUNDAI
C — Chassis
CAN Timeout EMS | Lost Communication with ECM | CAN Time-out EMS | Vehicle signal(VSS) time out
Views:
UK: 13
EN: 29
RU: 14
AI status
Completed
Completed
100%
Causes
- Open, shorted or high‑resistance CAN H/L wiring or damaged harness
- Poor or corroded connectors or pins at ECM or intermediate modules
- ECM loss of power or ground (fuse, relay, battery connection)
- Missing or incorrect CAN bus termination (open/shorted 120Ω resistors)
- Faulty ECM or other module that drives the CAN bus
- Intermittent faults from chafed wiring or aftermarket devices
Symptoms
- MIL/ABS/ESC or other warning lamps illuminated
- No vehicle speed display or erratic speedometer
- Cruise control, transmission shift logic, ABS or stability functions disabled or degraded
- Loss of specific functions controlled by ECM
- Intermittent module communication errors on a scan tool
What to check
- Read and record all DTCs and freeze frame data with a capable diagnostic scanner
- Verify battery voltage (should be >12.4 V at idle and >11 V cranking) and check charging system
- Inspect fuses and relays supplying ECM and CAN power/ground
- Visually inspect CAN wiring, connectors and grounds for damage, corrosion or loose pins
- Check for other related communication DTCs (U-codes or other C-codes)
- Measure CAN bus idle voltages and bus resistance with key off
Signal parameters
- CAN bus idle voltage (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (verify with vehicle spec)
- CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
- Bus termination: total between CAN_H and CAN_L ≈ 60 Ω (two 120 Ω resistors in parallel) with key off
- Typical CAN data rates: common values 250 kbps or 500 kbps — confirm vehicle specification
- VSS message rate varies with vehicle speed (frequency increases with speed) — expect speed-related message IDs on bus
Diagnostic algorithm
- Connect a professional scan tool and confirm C1611 plus any related DTCs and freeze frame data. Note which modules respond on the tool.
- Check battery, main fuses and ECM power/ground circuits. Repair any power/ground issues before proceeding.
- Inspect physical wiring and connectors at ECM, instrument cluster, ABS, TCM and other CAN nodes for damage or corrosion; reseat connectors.
- With ignition on, verify communication to ECM with the scan tool. If ECM is not responding, check for blown fuse or loss of power/ground at ECM connector pins.
- Measure CAN_H and CAN_L idle voltages and resistance between them (expect ~60 Ω). If voltages or resistance are out of range, isolate by disconnecting modules one at a time to find the faulty node or short.
- Use an oscilloscope or CAN bus analyzer to view waveforms and message traffic. Look for missing VSS/ECM messages, bus noise, dominant stuck states or irregular frames.
- Perform a wiggle test on suspect harness sections while monitoring for changes in communication or DTCs to locate intermittent faults.
- Repair/replace damaged wiring, connectors or termination resistors. If a single module is confirmed to be the source (no other way around wiring/termination), follow OEM procedures to repair or replace the module.
- After repairs, clear DTCs and verify normal communication and vehicle operation on a test drive. Re-scan to confirm no reoccurrence.
Likely causes
- Faulty or loose connector at the ECM or instrument cluster
- Open or short on CAN High or CAN Low between modules
- Blown fuse or poor ground causing ECM to be unpowered
- Damaged harness where it passes through pinch points or doors
- Failed ECM (less common) or other module blocking CAN traffic
Fault status
Status
Lost communication with ECM (CAN timeout) — expected Vehicle Speed Signal (VSS) or ECM messages not received.
Repair difficulty: Medium
Diagnostic time: 1.5-4.0 hours
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