B12D2

Code

LAND ROVER B — Body

Screen on / off LED

Brand: LAND ROVER

Type: B — Body

Views: UK: 16 EN: 27 RU: 19

AI status

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Page language: EN

Causes

Failed LED or LED assembly
Broken or corroded wiring or connector to the LED
Poor or open ground
Blown fuse or interrupted power feed
Faulty body control module (BCM) or display control module
Software/configuration fault or lost communication (CAN/LIN)

Symptoms

Screen on/off LED permanently off
Screen on/off LED permanently on or stuck flashing
LED works intermittently or only after moving connector
Associated instrument/display messages or errors
Potential related screen power or responsiveness issues

What to check

Read vehicle memory with a capable diagnostic tool; record all related DTCs and module status
Visual inspection of LED, display assembly and connectors for damage or corrosion
Check relevant fuses and relays for the display/screen circuits
Inspect wiring harness for chafing, breaks or aftermarket modifications
Verify module communication on CAN/LIN bus (no communication errors)

Signal parameters

Supply voltage to LED: ~12 V nominal (verify with multimeter)
Expected LED forward voltage: typically 2–3 V for small indicator LEDs (module may use resistor or driver)
Control type: direct battery feed switched by module or LED driver/PWM from control module (measure presence/absence when toggled)
Typical LED drive current: low mA range (10–50 mA) depending on design

Diagnostic algorithm

Use an OEM-capable scan tool; read and record DTC B12D2 and any related codes from BCM, infotainment/display module and instrument cluster.
Confirm software level and known technical service bulletins; reprogram modules if a software fix is available.
Perform a visual inspection: check connectors, wiring, and the screen assembly for physical damage or corrosion.
Verify fuses and power supply to the display/LED circuit; restore if blown and investigate cause.
With ignition on, backprobe the LED connector: check for battery voltage on the supply pin and a ground or PWM control on the control pin while toggling the screen on/off.
Measure continuity between the LED connector and the controlling module; inspect for short to ground or battery.
If wiring and power/ground are correct but LED does not respond, swap or bench-test the display/LED assembly if possible, or temporarily substitute a known-good unit.
If LED assembly is confirmed faulty replace it; if control signal missing, investigate/reprogram or replace the controlling module per OEM procedure.
Clear codes and verify repair by cycling screen on/off and performing a road or function test to ensure code does not return.

Likely causes

Open or short in LED supply or ground circuit
Connector corrosion or pin damage at the display assembly
Defective LED backlight or control PCB in the screen assembly
Intermittent module communication preventing proper LED control

Fault status

⚠️ Status

B12D2 — Screen On/Off LED circuit fault detected (indicator lamp not behaving as expected).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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Repair manuals

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LAND ROVER

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