B12F3

Code

LAND ROVER B — Body

Secondary release of the rear door

Brand: LAND ROVER

Type: B — Body

Views: UK: 18 EN: 24 RU: 17

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Page language: EN

Causes

Faulty rear door latch/actuator (secondary release mechanism)
Damaged or corroded wiring/connector in the rear door harness
Failed door position or latch sensor (switch)
Poor power/ground supply to latch actuator
Body Control Module (BCM) or door module software/control fault
Mechanical obstruction or seized latch

Symptoms

Rear door does not unlatch with remote/inside handle (secondary release)
Intermittent unlatch operation or only partial release
Instrument cluster message or audible alert about door not closed/unlatched
DTC B12F3 stored in BCM/door module

What to check

Scan vehicle with OEM-level diagnostic tool: read DTCs, freeze frame and live data for rear door command and feedback
Visually inspect rear door latch, actuator and connector for damage, corrosion, water ingress and foreign objects
Operate secondary release while watching live data to confirm command vs feedback
Check fuses and relays related to door module/BCM circuits
Inspect wiring in door hinge/boot area for chafe or broken conductors

Signal parameters

Actuator supply voltage: ~12 V when command issued (measure at latch connector)
Ground present at actuator common/return when commanded
Actuator resistance (typical latch motors/coils): low ohms to tens of ohms (check OEM spec before replacement)
Door position/latch switch: open/closed digital state reported to module (0/1) or via CAN/LIN message

Diagnostic algorithm

Connect an OEM-level scan tool and record B12F3 plus any related codes. Note vehicle behavior and freeze frame data.
Attempt secondary release command from the scanner; observe live data: does the module send a command and does the latch report a change?
Visually inspect latch/actuator and connector for damage, corrosion or water. Clear debris and dry/lubricate latch if contaminated.
Back-probe the latch connector while operating the command: verify 12 V supply and good ground when commanded. If no command voltage, check upstream wiring and module outputs.
If supply/ground present but actuator does not move, measure actuator resistance. If out of spec or open/short, replace latch/actuator.
If actuator works bench-tested but operation fails only on-vehicle, check for mechanical binding in the latch mechanism and correct alignment.
If wiring or intermittent fault suspected, perform continuity/insulation tests through door hinge area. Repair/replace damaged wiring harness as needed.
If wiring and latch are good but fault persists, check BCM/door module communication (CAN/LIN) and related codes (e.g., U-codes). Reprogram or replace module only after confirming hardware fault.
After repairs, clear codes, perform function test and cycle door operations multiple times. Confirm no reoccurrence and that no additional related codes return.

Likely causes

Failed rear door latch/actuator
Damaged wiring or connector at the door (pinched/chafed)
Door latch position switch fault

Fault status

⚠️ Status

Secondary release of rear door — release operation failed or feedback invalid. Inspect rear door latch/actuator, wiring and door module communications.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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Repair manuals

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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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