U0216

Code

Generic U — Network/User

Lost Communication With Door Switch B

Brand: Generic

Type: U — Network/User

Views: UK: 26 EN: 57 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in door switch wiring/harness
Failed door switch (mechanical/electrical)
Corroded or damaged door connector (hinge area)
Faulty Body Control Module (BCM) or other module that monitors the switch
CAN/LIN network fault or message loss
Blown fuse or loss of power/ground to relevant module

Symptoms

Door ajar indicator lamp may be incorrect for the affected door
Interior lights or dome lamp behavior abnormal (stay on or off)
Door lock/unlock or keyless entry functions for that door may not work
Alarm/immobilizer or remote-locking may show faults
Code present as active or intermittent; may coincide with other U-codes
Possible intermittent behavior with door open/close detection

What to check

Use a scan tool to read U0216 and any related codes, note whether Active or History
Check for other U‑codes (CAN network) that indicate broader communication problems
Visually inspect door harness at hinge, door switch and connector for damage/corrosion
Verify relevant fuses and module power/ground circuits
Backprobe switch connector and observe live data while operating the door/switch
Wiggle the door harness and connectors while watching live data for intermittent faults

Signal parameters

Door switch is typically a digital/open-closed circuit: expected states are 'open' (pulled high to battery or module pull-up) and 'closed' (pulled to ground).
Typical voltages: open ≈ battery voltage (9–14 V) or logic pull-up (5 V) depending on design; closed ≈ 0 V. Confirm with vehicle-specific wiring diagram.
If the switch reports via LIN or CAN, expect periodic or event-driven messages; absence of that message indicates a communication fault.
CAN bus idle voltage approx. 2.5 V on each line; differential voltage about 0 V idle and swings when transmitting — check with scope or CAN tester for traffic and termination faults.

Diagnostic algorithm

Connect a factory-grade scan tool. Record U0216 details, freeze frame, and any simultaneous codes.
Check vehicle-specific wiring diagram to determine whether the door switch is a direct input to the BCM or reported over LIN/CAN.
Visually inspect the door switch, connector and the door hinge harness for wear, pin corrosion, or water intrusion. Repair any visible damage.
Verify power and ground to the BCM and to the switch circuit (if wired). Check related fuses.
Backprobe the switch connector. Observe voltage/state while operating the switch and door. Confirm expected open/closed voltages per vehicle documentation.
If intermittent, perform a wiggle test of the door harness while monitoring live data for signal dropouts. Pay attention to harness at door hinge where wiring flexes.

Likely causes

Broken or chafed conductor in the door harness at the door hinge
Poor pin contact or corroded connector at the door switch or BCM connector
Door switch stuck or internally failed (intermittent contact)
Open or high-resistance ground or missing 12 V supply to the switch/BCM
Faulty BCM or other module not transmitting/receiving messages
CAN/LIN bus wiring short, open, or missing termination causing loss of message

Fault status

⚠️ Status

Lost communication with Door Switch B — module did not receive expected switch status or network message for Door Switch B.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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