C1809

Code

HYUNDAI C — Chassis

CAN time-out PSB

Brand: HYUNDAI

Type: C — Chassis

Views: UK: 15 EN: 20 RU: 17

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Page language: EN

Causes

Intermittent or open/shorted CAN-H or CAN-L wiring between PSB and gateway/ECUs
Loose, corroded or disconnected connector at PSB or nearby junctions
Faulty PSB (power steering) control module or gateway module
Poor battery/ignition voltage or ground causing module reset
Missing/incorrect CAN termination (open/mismatched 120 Ω resistors)
Recent module replacement or software mismatch causing message ID differences

Symptoms

Steering assist reduced or lost (may be intermittent)
Instrument cluster or steering-related warning lamp(s) illuminated
Other modules report lost communication or multiple CAN-related codes
Vehicle may experience limp steering or degraded stability functions
Symptoms often occur intermittently or under vibration/turning the steering wheel

What to check

Read all stored and pending codes on all networked modules with a scan tool; note freeze frame and occurrence counts
Verify battery voltage stable (12.2–14.5 V) with engine off and while cranking; check charging system
Visually inspect CAN wiring harnesses, connectors, and grounds around the steering column, PSB module, and gateway for damage, corrosion, or loose pins
Inspect fuses and relays related to steering/control modules
With key ON (engine off), monitor CAN network on scan tool for presence of PSB module and related message traffic
Check for recent module replacements or software updates that may change message IDs or baud rate

Signal parameters

CAN bus idle voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each to chassis) with differential near 0 V idle
Dominant state differential: CAN_H ≈ 3.5–4.0 V, CAN_L ≈ 1.0–1.5 V during transmission
Termination resistance: ≈ 60 Ω measured between CAN_H and CAN_L with power off (two 120 Ω in parallel)
Expected PSB-related message interval: typically 10–200 ms (timeouts commonly flagged when messages missing >~500–1000 ms)
Bus bitrate: vehicle-specific (commonly 250 kbps or 500 kbps on ABS/steering networks); mismatch will prevent communication

Diagnostic algorithm

Connect OEM-level scan tool and read all CAN and steering-related modules; record code C1809 details and any U-/C-codes reported by other modules.
Verify battery and charging system health; low voltage can cause module dropouts. Recharge or load-test battery if needed.
With ignition ON, monitor live CAN traffic. Confirm whether PSB module(s) appear and whether their message stream is continuous or drops out.
Perform a visual inspection of wiring and connectors for the PSB module, steering column, and gateway; repair any damage or corrosion.
Power down vehicle and measure termination resistance between CAN_H and CAN_L at convenient connector: expect ≈60 Ω. If open or incorrect, trace termination resistor circuit.
Backprobe CAN_H and CAN_L at PSB connector with oscilloscope while cranking/operating to view waveform quality, differential amplitude, and noise. Look for glitches, bus-off events, or missing frames.
If waveform and wiring good, try isolating the network: disconnect downstream modules one at a time (or isolate branches) to identify if a specific module causes bus timeout. Reconnect after each test.
Check grounds for the PSB and related modules; clean and tighten as needed.
If wiring, termination and power/ground are good and module still times out, consider reflashing software or replacing the PSB module per manufacturer procedures. After repair, clear codes and road-test to confirm resolution.
Document repairs and re-scan all modules for related codes; ensure software/calibrations match vehicle configuration.

Likely causes

Damaged or disconnected CAN wiring/connectors near steering column
Faulty PSB control module (intermittent)
Poor ground or low battery voltage causing module to stop transmitting
Open or incorrect CAN termination resistor value

Fault status

⚠️ Status

C1809 — CAN timeout detected for PSB. The PSB module is not receiving or transmitting expected CAN frames within the configured timeout period; communication with the steering subsystem is impaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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