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Home / DTC / B1559 — Door Key Barrel - Circuit Failure

B1559 — Door Key Barrel - Circuit Failure

Detailed page for trouble code B1559.

34,405codes
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22,491specific
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Code

B1559

LAND ROVER B — Body

Door Key Barrel - Circuit Failure

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

Causes

  • Open or shorted wiring to the door key barrel switch
  • Corroded, loose or damaged connector at the key barrel or BCM
  • Failed key barrel internal switch (mechanical/electrical failure)
  • Blown fuse or poor ground for the circuit
  • Water ingress or contamination in the door lock assembly
  • BCM input fault or software anomaly

Symptoms

  • Key barrel does not operate central locking for that door
  • No lock/unlock reaction when key turned in that door (electrical functions)
  • Door lock actuator does not respond from mechanical key input
  • Alarm may not arm/disarm correctly from that door
  • Intermittent or no communication logged for the door lock input in diagnostics

What to check

  • Visually inspect key barrel, lock cylinder and wiring for damage, corrosion or water ingress
  • Check and wiggle the harness connector at the lock cylinder and at the BCM for secure connection and corrosion
  • Check related fuses and relays for continuity and correct ratings
  • Use a diagnostic scanner to read live data and confirm B1559 and any related codes; observe lock input signal while operating key barrel
  • Measure voltage/continuity on the wiring between the lock switch and BCM while operating the key barrel
  • Inspect door wiring harness routes for chafing at hinge/door jamb

Signal parameters

  • Typical expected: open/closed switch — continuity (near 0 ohms) when key barrel switched, open (infinite) when not; when driven by 12V supply expect 0 V (ground) or +12 V depending on vehicle design when activated
  • Voltage at connector with ignition off: ~0–12 V depending on circuit type; while key turned expect a clear change in voltage/state
  • If signal is CAN or LIN based, expect corresponding message/bit to change in live data when the key barrel is operated

Diagnostic algorithm

  1. Retrieve and record freeze frame and any additional DTCs with a compatible diagnostic scanner; clear codes then reproduce and re-scan.
  2. Visual inspection: check key barrel, lock housing and connectors for corrosion, damage or water. Repair/replace any damaged wiring or connectors.
  3. Check fuses/relays for the door locking circuit; replace any blown fuses and test again.
  4. Backprobe the lock switch connector and observe signal with a multimeter/oscilloscope while operating the mechanical key barrel. Note whether the signal changes state as expected.
  5. If no signal change, test continuity between the lock switch and BCM input pins; repair any open or short circuits found.
  6. If wiring and connector are good but no correct switch behavior, remove the lock cylinder/assembly and bench-test the internal switch; replace the key barrel/lock assembly if faulty.
  7. If switch and wiring test OK, check BCM input for proper reference voltage/ground and update or reprogram BCM if manufacturer procedure indicates; consider replacing BCM only after all other causes are excluded.
  8. After repair, clear codes and verify proper operation of the key barrel and central locking; road test to confirm no recurrence.

Likely causes

  • Corroded/loose connector at the door lock cylinder
  • Broken or chafed wire between the door lock and BCM
  • Failed microswitch inside the key barrel (common with wear or moisture)
  • Blown fuse or poor ground in the door locking circuit

Fault status

⚠️ Status
Door key barrel circuit failure — BCM not detecting expected lock cylinder signal. Check lock cylinder, wiring, connectors and fuses.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 1.5 hours

Similar codes

B1558 B1560 B1574 B1590
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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Code

B1559

MITSUBISHI B — Body

Cut off for driver front Airbag

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

Causes

  • Open or shorted wiring to the door key barrel switch
  • Corroded, loose or damaged connector at the key barrel or BCM
  • Failed key barrel internal switch (mechanical/electrical failure)
  • Blown fuse or poor ground for the circuit
  • Water ingress or contamination in the door lock assembly
  • BCM input fault or software anomaly

Symptoms

  • Key barrel does not operate central locking for that door
  • No lock/unlock reaction when key turned in that door (electrical functions)
  • Door lock actuator does not respond from mechanical key input
  • Alarm may not arm/disarm correctly from that door
  • Intermittent or no communication logged for the door lock input in diagnostics

What to check

  • Visually inspect key barrel, lock cylinder and wiring for damage, corrosion or water ingress
  • Check and wiggle the harness connector at the lock cylinder and at the BCM for secure connection and corrosion
  • Check related fuses and relays for continuity and correct ratings
  • Use a diagnostic scanner to read live data and confirm B1559 and any related codes; observe lock input signal while operating key barrel
  • Measure voltage/continuity on the wiring between the lock switch and BCM while operating the key barrel
  • Inspect door wiring harness routes for chafing at hinge/door jamb

Signal parameters

  • Typical expected: open/closed switch — continuity (near 0 ohms) when key barrel switched, open (infinite) when not; when driven by 12V supply expect 0 V (ground) or +12 V depending on vehicle design when activated
  • Voltage at connector with ignition off: ~0–12 V depending on circuit type; while key turned expect a clear change in voltage/state
  • If signal is CAN or LIN based, expect corresponding message/bit to change in live data when the key barrel is operated

Diagnostic algorithm

  1. Retrieve and record freeze frame and any additional DTCs with a compatible diagnostic scanner; clear codes then reproduce and re-scan.
  2. Visual inspection: check key barrel, lock housing and connectors for corrosion, damage or water. Repair/replace any damaged wiring or connectors.
  3. Check fuses/relays for the door locking circuit; replace any blown fuses and test again.
  4. Backprobe the lock switch connector and observe signal with a multimeter/oscilloscope while operating the mechanical key barrel. Note whether the signal changes state as expected.
  5. If no signal change, test continuity between the lock switch and BCM input pins; repair any open or short circuits found.
  6. If wiring and connector are good but no correct switch behavior, remove the lock cylinder/assembly and bench-test the internal switch; replace the key barrel/lock assembly if faulty.
  7. If switch and wiring test OK, check BCM input for proper reference voltage/ground and update or reprogram BCM if manufacturer procedure indicates; consider replacing BCM only after all other causes are excluded.
  8. After repair, clear codes and verify proper operation of the key barrel and central locking; road test to confirm no recurrence.

Likely causes

  • Corroded/loose connector at the door lock cylinder
  • Broken or chafed wire between the door lock and BCM
  • Failed microswitch inside the key barrel (common with wear or moisture)
  • Blown fuse or poor ground in the door locking circuit

Fault status

⚠️ Status
Door key barrel circuit failure — BCM not detecting expected lock cylinder signal. Check lock cylinder, wiring, connectors and fuses.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 1.5 hours

Similar codes

B1558 B1560 B1574 B1590
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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Code

B1559

Other B — Body

Door Lock Cylinder Circuit Failure

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

Causes

  • Open or shorted wiring to the door key barrel switch
  • Corroded, loose or damaged connector at the key barrel or BCM
  • Failed key barrel internal switch (mechanical/electrical failure)
  • Blown fuse or poor ground for the circuit
  • Water ingress or contamination in the door lock assembly
  • BCM input fault or software anomaly

Symptoms

  • Key barrel does not operate central locking for that door
  • No lock/unlock reaction when key turned in that door (electrical functions)
  • Door lock actuator does not respond from mechanical key input
  • Alarm may not arm/disarm correctly from that door
  • Intermittent or no communication logged for the door lock input in diagnostics

What to check

  • Visually inspect key barrel, lock cylinder and wiring for damage, corrosion or water ingress
  • Check and wiggle the harness connector at the lock cylinder and at the BCM for secure connection and corrosion
  • Check related fuses and relays for continuity and correct ratings
  • Use a diagnostic scanner to read live data and confirm B1559 and any related codes; observe lock input signal while operating key barrel
  • Measure voltage/continuity on the wiring between the lock switch and BCM while operating the key barrel
  • Inspect door wiring harness routes for chafing at hinge/door jamb

Signal parameters

  • Typical expected: open/closed switch — continuity (near 0 ohms) when key barrel switched, open (infinite) when not; when driven by 12V supply expect 0 V (ground) or +12 V depending on vehicle design when activated
  • Voltage at connector with ignition off: ~0–12 V depending on circuit type; while key turned expect a clear change in voltage/state
  • If signal is CAN or LIN based, expect corresponding message/bit to change in live data when the key barrel is operated

Diagnostic algorithm

  1. Retrieve and record freeze frame and any additional DTCs with a compatible diagnostic scanner; clear codes then reproduce and re-scan.
  2. Visual inspection: check key barrel, lock housing and connectors for corrosion, damage or water. Repair/replace any damaged wiring or connectors.
  3. Check fuses/relays for the door locking circuit; replace any blown fuses and test again.
  4. Backprobe the lock switch connector and observe signal with a multimeter/oscilloscope while operating the mechanical key barrel. Note whether the signal changes state as expected.
  5. If no signal change, test continuity between the lock switch and BCM input pins; repair any open or short circuits found.
  6. If wiring and connector are good but no correct switch behavior, remove the lock cylinder/assembly and bench-test the internal switch; replace the key barrel/lock assembly if faulty.
  7. If switch and wiring test OK, check BCM input for proper reference voltage/ground and update or reprogram BCM if manufacturer procedure indicates; consider replacing BCM only after all other causes are excluded.
  8. After repair, clear codes and verify proper operation of the key barrel and central locking; road test to confirm no recurrence.

Likely causes

  • Corroded/loose connector at the door lock cylinder
  • Broken or chafed wire between the door lock and BCM
  • Failed microswitch inside the key barrel (common with wear or moisture)
  • Blown fuse or poor ground in the door locking circuit

Fault status

⚠️ Status
Door key barrel circuit failure — BCM not detecting expected lock cylinder signal. Check lock cylinder, wiring, connectors and fuses.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 1.5 hours

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