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Home / DTC / B2856 — Room Mirror Push SW Type Stuck Error

B2856 — Room Mirror Push SW Type Stuck Error

Detailed page for trouble code B2856.

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Code

B2856

HYUNDAI B — Body

Room Mirror Push SW Type Stuck Error

Brand: HYUNDAI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Mechanical binding or foreign object preventing switch movement
  • Failed or worn switch contacts (internal short or open)
  • Corroded or damaged connector/pins at mirror or switch
  • Damaged wiring harness (short to power/ground or open)
  • Water intrusion or contamination in mirror/switch assembly
  • Faulty body/BCM or mirror control module software/hardware

Symptoms

  • DTC B2856 stored and/or instrument cluster message
  • Mirror push switch does not change state or is unresponsive
  • Power fold or mirror adjustment not functioning correctly
  • Intermittent operation or operation only after manipulating mirror/switch
  • Possible visible corrosion or moisture at mirror connector

What to check

  • Read and record DTC(s) and freeze frame with a capable scan tool; note conditions
  • Visually inspect mirror assembly, switch, and wiring for damage, corrosion, or water
  • Operate the mirror push switch and observe switch operation and mirror response
  • Check the mirror connector for bent pins, corrosion, and secure fit
  • Measure battery voltage at the mirror connector while operating the switch
  • Check for related codes in BCM or other modules (CAN communication errors)

Signal parameters

  • Switch input state (logical open/closed or monitored voltage level) reported to BCM
  • Battery voltage (approx. 12 V) at power pins when ignition ON
  • Continuity/resistance across switch terminals (closed ≈ low ohms, open ≈ high/infinite)
  • CAN/BUS messages from mirror module or BCM when operating switch
  • Motor current draw or fold motor movement when commanded (if applicable)

Diagnostic algorithm

  1. With scan tool, clear codes and attempt to reproduce the fault by operating the mirror push switch several times. Note if code returns.
  2. Perform a visual inspection of the mirror housing, switch, and connectors for contamination, damage, or water entry. Repair visible damage.
  3. Operate the switch while backprobing the switch connector: verify expected voltage or signal change. Compare to battery voltage and expected open/closed behavior.
  4. Check continuity/resistance of the switch terminals with the switch actuated and released. Replace switch if contacts do not change state.
  5. Inspect wiring harness from mirror to BCM for chafing, breaks, or corrosion. Repair any damaged wiring or connectors.
  6. If wiring and switch test good, command mirror fold/unfold with a scan tool and monitor inputs/outputs and any motor current. If motor is jammed, free or replace mirror assembly.
  7. If all hardware checks OK, inspect BCM/mirror module for software updates or known service bulletins; reprogram or replace module only after confirming wiring/switch integrity.
  8. After repairs, clear codes, perform functional test cycles, and confirm the DTC does not return.

Likely causes

  • Stuck plunger or actuator inside the mirror push switch
  • Corroded connector pins at the mirror or in the harness
  • Short circuit between switch signal and battery/ground
  • Mirror assembly motor or mechanism jam causing switch to remain engaged

Fault status

⚠️ Status
Room mirror push switch circuit indicates a stuck or unchanging input; switch remains in one state or reports out-of-range values.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B2850 B2851 B2855 B2857 B2860
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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