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Home / DTC / B2990 — Knee support - short circuit to the ground

B2990 — Knee support - short circuit to the ground

Detailed page for trouble code B2990.

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Code

B2990

LAND ROVER B — Body

Knee support - short circuit to the ground

Brand: LAND ROVER
Type: B — Body
Views: UK: 6 EN: 12 RU: 10
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Page language: EN

Causes

  • Chafed or damaged wiring harness with conductor contacting chassis ground
  • Corroded or contaminated connector causing low-resistance path to ground
  • Knee airbag squib (inflator) internally shorted to ground
  • Poor previous repair or pinched wiring after seat/body service
  • Water ingress or contamination in connector or harness
  • Faulty SRS/knee support module or internal short

Symptoms

  • SRS / airbag warning lamp illuminated on dash
  • Knee airbag disabled (fault stored), possible disablement of other airbags
  • Stored DTC B2990 in SRS control module
  • Possible intermittent SRS lamp depending on harness movement

What to check

  • Read and record all stored SRS codes and freeze-frame data with a capable scan tool
  • Verify battery voltage and condition (stable 12 V) before SRS diagnostics
  • Visually inspect knee airbag connector and wiring for damage, corrosion, moisture or loose pins
  • Inspect routing of harness where it passes over seat frames, brackets, and through grommets
  • Check for aftermarket accessories or previous repair areas near the knee harness
  • Measure continuity/resistance of squib circuit and continuity to chassis ground (with SRS system disabled)

Signal parameters

  • Squib loop resistance (typical good range): approx. 2–5 ohms (consult vehicle spec)
  • Short-to-ground condition: very low resistance (~0–1 ohm) between squib circuit pin and chassis ground
  • Open circuit: infinite/OL between squib pins or between squib pin and module
  • SRS module ground:
  • Module supply voltage: battery voltage present at SRS power feed with ignition on (~12 V)

Diagnostic algorithm

  1. Safety first: follow manufacturer SRS safety procedures. Disable the SRS system and disconnect the battery as specified in the service manual before probing connectors or performing resistance checks.
  2. Connect a diagnostic scan tool capable of reading Land Rover SRS codes. Read and note all stored codes, freeze-frame data, and module status.
  3. Visually inspect the knee airbag connector, wiring, and harness routing for damage, corrosion, moisture or pinched areas. Pay attention where the harness passes under the dash, around seat mounts and through grommets.
  4. With SRS disabled and battery disconnected per procedures, disconnect the knee airbag connector. Measure resistance between the squib pins (inflator pins) and compare to specification. A very low resistance to chassis ground indicates a short-to-ground.
  5. Measure resistance between each squib pin and chassis ground. If near 0 ohms, trace the harness toward the chassis following the continuity to the grounding point until the short location is found.
  6. If no short to ground at the connector, disconnect the SRS control module (or intermediate connectors) and measure at both ends to isolate whether the fault is in feed side, module side or harness section.
  7. Inspect and wiggle-test harness while monitoring resistance or live fault on scan tool to catch intermittent shorts from movement.
  8. Repair any damaged wiring or connectors — replace harness section or install new terminals, protect repaired section with correct grommets and routing. Replace the knee airbag squib only if testing indicates internal short or manufacturer guidance requires replacement.
  9. After repairs, reconnect system, restore battery and SRS connections, clear codes with the scan tool and perform SRS system self-check. Verify that the B2990 code does not return and that the SRS lamp extinguishes.
  10. If code persists after harness/connector/squib checks and repair, consider module fault and consult manufacturer diagnostics for SRS/knee support module testing or replacement.

Likely causes

  • Insulation abrasion where wiring passes near seat frame or dash bracket
  • Connector terminal corrosion allowing current to leak to ground
  • Broken wire rubbed through to vehicle body at a harness grommet
  • Shorted squib due to impact damage or manufacturing fault
  • Loose or improperly seated connector at the knee airbag or SRS module

Fault status

⚠️ Status
Knee support circuit: short circuit to ground detected. SRS control module has stored fault B2990. Inspect knee airbag wiring, connector and squib for short to chassis.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B0001 B0002 B0020 B0025 B1233
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