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Home / DTC / B1166 — Front right headlight output

B1166 — Front right headlight output

Detailed page for trouble code B1166.

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Code

B1166

LAND ROVER B — Body

Front right headlight output

Brand: LAND ROVER
Type: B — Body
Views: UK: 3 EN: 10 RU: 9
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Page language: EN

Causes

  • Blown fuse or faulty relay for headlamps
  • Failed headlamp bulb or LED module
  • Damaged wiring harness or poor connector at right headlamp
  • Corroded or poor ground connection
  • Faulty body control module / headlamp driver module
  • Software/firmware issue in BCM or headlamp control

Symptoms

  • Right front headlight inoperative (low beam, high beam or DRL depending on circuit)
  • Flickering or intermittent operation of right headlamp
  • Other lighting-related warnings or DIC messages
  • Related DTCs logged in body control or lighting modules

What to check

  • Read stored DTCs and freeze frame data with a compatible diagnostic scanner
  • Verify which lamp function is affected (low beam, high beam, DRL, turn, etc.)
  • Visually inspect right headlamp, lens and harness for damage or moisture
  • Check fuses and relays for headlamp circuits
  • Inspect connector at lamp for corrosion, bent pins, or poor fit
  • Compare behavior of left and right lamps (swap bulbs if serviceable)

Signal parameters

  • Expected supply voltage at headlamp connector: battery voltage ~11–14.5 V with ignition on
  • Typical halogen bulb current: ~4–6 A at 12 V (approx. 55 W bulb)
  • LED module current: usually lower (manufacturer-specific), often 0.5–5 A; consult vehicle spec
  • Open-circuit resistance to bulb filament (halogen) should be low (a few ohms) when cold; infinite if filament open
  • If PWM-driven: switching frequency often tens to hundreds Hz and duty varies with brightness (refer to OEM spec)

Diagnostic algorithm

  1. Connect a diagnostic scanner and record all lighting-related DTCs and freeze-frame data. Clear codes and re-run to confirm repeatability.
  2. Identify which headlamp function (low, high, DRL) is affected from live data. Verify whether left lamp of same circuit functions normally.
  3. Visually inspect the right headlamp assembly, connector and wiring for damage, corrosion or moisture. Repair any obvious physical defects.
  4. With ignition on and lamp function commanded on, measure battery voltage at the headlamp connector power pin and ground pin. If no battery voltage, check upstream fuse/relay and continuity to fuse.
  5. Check continuity from the headlamp connector ground to vehicle chassis ground. Clean and secure ground if high resistance or corrosion is found.
  6. If lamp type is replaceable bulb: remove and bench-test or swap with known good bulb from the left side. If fault follows bulb, replace bulb/module.
  7. If voltage present but lamp does not light and bulb is good, measure current draw (or use an appropriate clamp meter) and look for PWM signal if applicable. Compare to expected values.
  8. Inspect connector pins for high resistance/wear. Wiggle test wiring while observing live data or lamp behavior to find intermittent faults.
  9. If wiring and lamp verify OK, perform module-level tests: check BCM output driver status and related inputs (CAN/LIN communication). Check for software updates or TSBs affecting headlamp control.
  10. If BCM or headlamp driver is suspected, perform recommended OEM module tests. Replace module only after confirming wiring and lamp integrity; reprogram/recode replacement modules per manufacturer.
  11. After repairs, clear codes and verify lamp operation under different conditions; confirm no recurrence of B1166.

Likely causes

  • Open or short in right headlamp output circuit
  • Defective right headlamp bulb/module (filament open, LED driver failed)
  • Corroded connector or broken pin at lamp harness
  • Failed headlamp driver inside BCM or separate headlamp control module

Fault status

⚠️ Status
Front right headlight output circuit fault detected — check right headlamp, connector, wiring, fuses/relays and control module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B1164 B1165 B1167 B1168 C1234
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