B1C40

Code

LAND ROVER B — Body

Key release switch

Brand: LAND ROVER

Type: B — Body

Views: UK: 19 EN: 27 RU: 23

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Page language: EN

Causes

Faulty key release switch (mechanical or electrical failure)
Damaged or corroded connector or wiring (open, short to ground/voltage, intermittent)
Poor or missing ground at switch or control module
Faulty Body Control Module (BCM) or related control module
Software/firmware issue or configuration error
Water ingress or contamination at the switch or connector

Symptoms

Key release/insert function not working or intermittent (key may not release from ignition)
Warning message or indicator related to key, ignition or immobilizer
Key removal/insert may feel sticky or mechanically obstructed
Vehicle may fail to accept key or not switch between accessory/ignite positions as expected
Possible stored additional communication or body control codes

What to check

Retrieve and record freeze frame and all stored DTCs with an OEM-capable scanner
Visually inspect key release switch, surrounding trim, and wiring harness for damage, corrosion, or water ingress
Check connectors for secure fit and bent pins at switch and BCM
Verify battery voltage is within specification during tests (typically ~12–14 V)
Check for related communication codes (U-codes) that could indicate BCM or network issues

Signal parameters

Switch state: closed/open depending on key position (expected binary). Use scanner or multimeter to confirm logical state changes when actuating switch
Supply voltage: ~12 V at the switch feed when ignition/vehicle power is on
Ground continuity: near 0 Ω between switch ground and chassis ground
Resistance: manufacturer-specific low resistance when closed (near 0 Ω); open circuit when released
CAN/BUS: BCM should report switch state changes on CAN — verify message presence with vehicle-specific tool

Diagnostic algorithm

Connect an OEM-capable diagnostic tool, read and record B1C40 and related codes and live data for the key release switch.
Attempt to reproduce fault and observe live data/switch state while operating key release; note if code sets immediately or intermittently.
Visually inspect switch, connectors and harness for damage, corrosion, moisture, or pin damage. Repair as needed.
With ignition off and battery safe, disconnect switch connector and inspect pins for corrosion or bent pins; reconnect to retest.
Probe the switch circuit: verify supply voltage at connector (with ignition on), verify ground continuity, and verify switch output toggles between expected voltages when actuated. Use backprobe or wiring diagrams to identify pins.
Check continuity/resistance of wiring between switch and BCM; repair any opens or shorts. Wiggle-test harness to find intermittent faults.
If wiring and switch pass, compare live input on BCM (or module input pins) to switch output. If switch output is correct but BCM input does not change, suspect module or CAN wiring.
Check for and repair any water ingress or contamination; replace switch if mechanical wear or internal corrosion found.
If electrical and mechanical items correct, perform module software update/reflash per manufacturer service info and clear codes; re-evaluate.
If problem persists after switch replacement and software update, perform module-level diagnostics or replace BCM as directed by manufacturer procedures.

Likely causes

Corroded/damaged connector or wiring between switch and BCM
Defective key release switch (worn contacts or stuck mechanism)
Intermittent short or open in harness at door/steering column area
Faulty BCM or software communication error

Fault status

⚠️ Status

Module detected an implausible, absent, or out-of-range signal from the key release switch circuit. The fault may be caused by the switch, wiring/connector issues, or module/communication problems.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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