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Home / DTC / B123B — Turn signal to change direction front to the right

B123B — Turn signal to change direction front to the right

Detailed page for trouble code B123B.

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Code

B123B

LAND ROVER B — Body

Turn signal to change direction front to the right

Brand: LAND ROVER
Type: B — Body
Views: UK: 9 EN: 72 RU: 8
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Page language: EN

Causes

  • Burnt or failed front right turn signal bulb or LED
  • Corroded or damaged lamp socket or connector
  • Open or short in the turn signal wiring (power or ground)
  • Poor ground at the front right lamp or chassis
  • Faulty body control module (BCM) or flasher/turn signal driver
  • Blown fuse or faulty relay associated with exterior lighting

Symptoms

  • Front right turn signal does not flash when signaling to the right
  • Turn indicator warning light on the dash may flash rapidly or not at all
  • Turn signal may work intermittently or only when wires are moved
  • Related lamps (parking or side marker) may also be inoperative
  • Possible stored or active BCM/lighting fault messages on the dash

What to check

  • Read and record all current and historic fault codes with a Land Rover-compatible scan tool
  • Visually inspect front right lamp, lens, and wiring for damage, water ingress, or corrosion
  • Inspect fuses and relays for the exterior lighting circuits
  • Check bulb/LED condition by removing the lamp and performing a bench test or swapping with the opposite side lamp
  • Measure voltage at the lamp connector with turn signal commanded (expected battery voltage ~11–14 V)
  • Check continuity and resistance of the wiring between the lamp connector and the BCM

Signal parameters

  • Supply voltage at lamp connector (when commanded): approx. 11–14 V
  • Bulb filament resistance (typical 21W indicator): roughly 2–3 Ω cold
  • LED lamp current: typically 50–300 mA per indicator (varies by lamp)
  • Expected flash rate: approximately 60–120 flashes per minute (1–2 Hz) on normal operation
  • Open-circuit: infinite resistance between power and lamp or between lamp and ground
  • Short-circuit: low resistance near 0 Ω from power to ground indicates short

Diagnostic algorithm

  1. Use a compatible diagnostic tool to read DTCs, freeze frame, and relevant data parameters. Note if B123B is active or historic. Clear the code and attempt to reproduce.
  2. Visually inspect the right front lamp assembly, lens seal, connector, and harness for damage or corrosion. Repair any obvious issues.
  3. With the ignition on and turn signal commanded to the right, check for voltage at the lamp connector pin for power and for continuity to ground. If voltage present and lamp removed, test the removed lamp on a bench or swap with left side lamp.
  4. If lamp works on bench or swap, inspect harness continuity between the lamp connector and the BCM. Perform wiggle tests while observing voltage or lamp behavior to find intermittent wiring faults.
  5. Check and test relevant fuses and relays. Replace if faulty.
  6. Verify ground integrity at the lamp mounting point; clean and tighten ground connections as required and re-test.
  7. If wiring, bulb, fuse and ground are good but fault persists, use a scan tool to command the BCM output and monitor the BCM output pin with a multimeter or oscilloscope. Compare to expected parameters.
  8. If BCM output is abnormal or non-responsive, check for communication errors on vehicle networks (CAN) and ensure software is up to date. Consider module reprogramming or replacement only after verifying all wiring and external components.
  9. After repair, clear codes, exercise turn signals and re-scan to ensure the fault does not return.

Likely causes

  • Failed bulb/LED lamp in front right turn signal
  • Corroded connector or broken wire at the lamp harness
  • Bad ground connection at the lamp mounting point
  • BCM output for the front right indicator is open or shorted
  • A blown fuse for external lamps or a failed turn-signal relay module

Fault status

⚠️ Status
Front right turn signal circuit fault detected — lamp not operating or circuit abnormal. Inspection of bulb, wiring, connector, ground and BCM output recommended.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B123A B123C B1230 B1240
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