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Home / DTC / B1A40 — Left side (pelvic) 2

B1A40 — Left side (pelvic) 2

Detailed page for trouble code B1A40.

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Code

B1A40

LAND ROVER B — Body

Left side (pelvic) 2

Brand: LAND ROVER
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in the left pelvic sensor wiring harness
  • Corroded, loose, or damaged connector at the sensor or SRS control module
  • Failed pelvic/occupant sensor (internal fault)
  • Water intrusion or contamination in the seat area
  • Faulty Body/SRS control module or internal connector fault
  • Incorrect sensor calibration or software fault after repair or module replacement

Symptoms

  • Illuminated SRS/Airbag warning light on dash
  • Possible passenger/seatbelt reminder or occupant detection warnings
  • Airbag system may disable side/pelvic deployment for the left seat
  • Stored DTC B1A40 (and possibly related SRS occupant-sensor codes)
  • Intermittent faults when seat is moved or pressure applied

What to check

  • Read all SRS/airbag codes with a capable scan tool; note freeze frame and related codes
  • Visually inspect left seat upholstery, connectors, and wiring harness for damage, corrosion or water
  • Check connector security at the pelvic sensor(s) under the seat and at the SRS module
  • Perform wiggle test of the seat harness while monitoring live data and code status
  • Verify reference voltage, signal voltage and ground at the sensor connector with ignition ON (use appropriate safety precautions)
  • Compare measured sensor parameters to known-good values or factory data

Signal parameters

  • Reference voltage: typically ~5.0 V (verify with factory data for model/year)
  • Sensor signal: typically a variable voltage signal in the range ~0.5–4.5 V depending on sensor and load
  • Signal resistance: occupant/pelvic sensors can show variable resistance; consult factory specs (common range depends on sensor design)
  • CAN/Module message: SRS module should poll/receive occupant classification updates at regular intervals — check for missing messages
  • Continuity: low ohm continuity expected between sensor ground and chassis ground (near 0–5 Ω)

Diagnostic algorithm

  1. Retrieve all related SRS codes and freeze frame with a diagnostic scan tool. Document before clearing.
  2. Visually inspect left seat area for water, corrosion, disconnected or damaged connectors and harness chafing.
  3. With battery charged and ignition ON (engine OFF), probe the pelvic sensor connector: verify reference voltage, signal voltage, and ground using factory pinout. Compare to known-good specs.
  4. Wiggle the harness and move the seat while watching live data and scan tool for changes or intermittent faults.
  5. If wiring/connector suspected, disconnect battery per safety procedures for SRS, then repair or replace damaged connectors/wiring. Recheck for shorts/opens and insulation damage.
  6. If wiring checks good, bench or substitute test the pelvic sensor (or swap with known-good if available) and re-scan — do not force sensor removal procedures that may deploy SRS components; follow OEM safety/service manual.
  7. If sensor replacement or module replacement performed, carry out required programming/calibration of the occupant classification system per manufacturer instructions.
  8. Clear codes and perform test drive or occupant-loading tests to confirm that B1A40 does not return and that SRS lamp behavior is normal.
  9. If the fault persists after sensor and wiring verification, escalate to SRS control module diagnostics or consult factory technical service information.

Likely causes

  • Broken or pinched wire in the seat harness near the seat rail
  • Corroded pins or poor mating at the seat pad connector
  • Failed pelvic sensor due to moisture ingress
  • Failed SRS control module input for that sensor circuit
  • Recent seat repair or replacement not reconnected or calibrated

Fault status

⚠️ Status
Left pelvic occupant sensor circuit fault detected (Left side pelvic sensor 2) — SRS/occupant classification may be disabled for that seating position.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B1A41 B1A42 B1A10 B1A00 B1620
320

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