U0518

Code

Generic U — Network/User

Invalid Data Received From Door Switch C

Brand: Generic

Type: U — Network/User

Views: UK: 26 EN: 48 RU: 29

AI status

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Page language: EN

Causes

Faulty door switch (mechanical or internal electrical failure)
Corroded, loose or damaged connector at the door switch
Broken, shorted, or high-resistance wiring between the switch and BCM
Poor ground or supply voltage to the switch or BCM
CAN/LIN bus communication errors (noise, bad termination, bus-off)
Faulty BCM or gateway module supplying/receiving the message

Symptoms

Door ajar indicator lamp may behave incorrectly (stays on, stays off, or flickers)
Interior lights or dome lamps may not work as expected
Central locking or keyless entry may not lock/unlock that door
One door not showing correct status in instrument cluster or infotainment
DTC stored and readiness/communication warnings on scan tool
Intermittent or permanent malfunction depending on cause

What to check

Read freeze frame and full DTC list with a scan tool; note any related network codes
Monitor live data for the door switch while operating the door (open/close) to see logical state changes
Inspect the switch connector and wiring for corrosion, bent pins, moisture, or damage
Perform a wiggle test on harness and connectors while observing live data or DTCs
Check supply voltage and ground at the switch connector with a multimeter
Measure continuity/resistance between the switch and BCM pin to check for opens or high resistance

Signal parameters

Door switch is typically a binary signal: closed (active) or open (inactive)
Switch types vary: may be contact-to-ground (closed ~0 V) or pulled-up to a logic voltage (closed ~0 V or 0/5 V logic). Confirm vehicle-specific wiring
Expected logical change when door is opened/closed (instant state flip with minimal bounce after debounce)
CAN message carrying the door status typically updates multiple times per second; persistent invalid packet or incorrect payload triggers U0518
If monitoring the bus with an oscilloscope, healthy CAN-H/CAN-L idle voltages ~2.5 V and clean differential signals; excessive noise or missing frames indicates bus problem

Diagnostic algorithm

Verify code and timestamp: connect a diagnostic scanner, record freeze frame and note any related U-codes.
Observe live data: open and close the affected door while watching the door switch status. Confirm whether the switch ever reports the correct state.
Visual inspection: inspect the door switch, door jamb area, and harness for damage, corrosion, or moisture. Repair or clean as needed.
Check connector/power/ground: with ignition on, measure supply voltage and ground at the switch connector. Repair poor power/ground.
Continuity test: disconnect battery if required, then check continuity/resistance between the switch terminals and BCM connector pin to identify opens or high resistance.
Bench or direct test the switch: where appropriate, actuate the switch and measure its output with a multimeter to confirm open/closed behavior.
Wiggle test while monitoring: manipulate wiring and connectors to reproduce the fault; observe DTC behavior and live data.
Inspect network: check for other communication codes. Use an oscilloscope or CAN bus tool to verify message integrity and termination. Repair any bus faults.
If wiring/switch are good, consider BCM or gateway fault: verify software calibration/part number and update/reflash per manufacturer procedures. Replace module only after confirming wiring and bus are good.
Clear codes and road-test: after repairs, clear DTCs and verify the fault does not return under normal operation.

Likely causes

Intermittent/poor connector at the door switch or wiring (most common)
Door switch failed (stuck, intermittent contact)
Wiring short to ground or to battery voltage
CAN bus communication problem or module fault
Faulty BCM or related gateway (less common)

Fault status

⚠️ Status

Invalid Data Received From Door Switch C — BCM detected implausible or corrupt data for the door switch signal or network message.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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