C181800

Code

HYUNDAI C — Chassis

CAN Time-Out LCA

Brand: HYUNDAI

Type: C — Chassis

Views: UK: 9 EN: 8 RU: 11

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Page language: EN

Causes

Corroded, loose or damaged CAN H/L wiring or connectors to the LCA module
Poor or intermittent ground or module power supply (battery/ignition feed)
Failed LCA module or failed CAN transceiver inside the module
Faulty termination resistor or short between CAN_H and CAN_L
High bus error rate or bus-off condition caused by another module
Aftermarket device or recent repairs that disturbed the CAN network

Symptoms

LCA / Lane Change Assist disabled message or warning light in instrument cluster
Loss of LCA functions (no lane change alert / assist)
Other modules reporting CAN communication DTCs or network warnings
Intermittent or permanent fault present after key cycles
Possible multiple body-network functions affected if bus fault is severe

What to check

Read all stored and pending DTCs with a manufacturer-capable scan tool; record freeze frame and CAN network errors
Verify the presence of the LCA module on the CAN network (module ID/address visible on scanner)
Check battery voltage and key-on supply to LCA module (normal ~11–15 V)
Visually inspect connectors and harness for damage, corrosion, water intrusion near LCA and gateway/BCM
Wiggle harness/connectors while watching live CAN messages to attempt to reproduce timeout
Measure CAN bus idle voltages at the LCA connector (CAN_H and CAN_L) and compare to reference values

Signal parameters

Battery/ignition supply to LCA: ~11–15 V (key on)
Ground reference: near 0 V (solid chassis ground)
CAN_H idle voltage: ~2.5 V (recessive); dominant ~3.5 V
CAN_L idle voltage: ~2.5 V (recessive); dominant ~1.5 V
CAN_H to CAN_L differential dominant ≈ 2.0 V
Total bus resistance measured end-to-end between CAN_H and CAN_L ≈ 60 ohms (two 120 Ω terminators in parallel)

Diagnostic algorithm

Connect a manufacturer-grade scan tool. Read and record all DTCs (stored, pending, history) and freeze frame data. Note related U- or C-codes.
Verify whether the LCA module is present/responding on the CAN network. If the module is not present, attempt to wake it (cycle ignition) and re-scan.
Clear the C181800 code and key-cycle. See if the code returns and under what conditions (immediate, after driving, after door cycle).
Inspect visually: connectors, pins, and wiring for the LCA module and junction points. Look for corrosion, bent pins, water entry, or chafing.
Check module supply and ground: measure key-on battery voltage at the module power terminal and verify solid ground at module ground terminal.
Measure CAN voltages at the module connector (CAN_H and CAN_L) with key on. Compare to expected idle and dominant levels. If voltages are abnormal, inspect wiring for short to battery/ground or to each other.
Measure resistance between CAN_H and CAN_L with ignition off. Expect ~60 Ω. If not, isolate wiring sections and check for open/short to chassis or 12 V.
Use an oscilloscope or CAN sniffer to view message traffic and error frames. Look for missing messages, dominant bus, bus-off events, or high error rates. If another node is pulling the bus dominant, disconnect suspected nodes one at a time to isolate.
Wiggle-test harness and connectors while monitoring CAN traffic to reproduce intermittent timeouts. Repair any damaged wiring or connectors.
If wiring and power/ground are good and the module is still not communicating, update module software per manufacturer TSB/SI and then consider replacing the LCA module or gateway as last resort. After repairs, reprogram/configure modules as required and verify no further timeouts.

Likely causes

Loose or corroded connector at LCA module
Damaged CAN pair (chafed, pinched, or water-damaged) between LCA and gateway/BCM
Failed LCA module CAN transceiver
Missing/failed ground or low supply voltage to LCA module
Open or shorted termination resistor

Fault status

⚠️ Status

C181800 — CAN Time-Out (LCA). LCA module messages not received on CAN bus within expected interval; LCA function disabled.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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