Code
B106D
LAND ROVER
B — Body
head retention switch
Views:
UK: 14
EN: 27
RU: 22
AI status
Completed
Completed
100%
Causes
- Faulty head restraint (head retention) switch
- Open, shorted or corroded wiring/connector between switch and restraint control module
- Poor ground or supply to the switch
- Water ingress or contamination of connector or switch
- Damage from seat removal/installation or impact
- Faulty restraint control module or related module software fault
Symptoms
- Restraint/airbag warning light illuminated
- Passive head restraint may not move or lock correctly
- Diagnostic trouble code B106D stored in restraint control module
- Possible related DTCs for other restraint/seat sensors
- Intermittent fault that may change with seat movement
What to check
- Read and record all DTCs and freeze‑frame data with a factory or dealer-level scan tool
- Visually inspect the head restraint switch and connector for damage, corrosion, moisture or foreign material
- Inspect seat and under‑seat wiring harness routing for chafe, pinch or connector damage
- Verify fuses and power/ground circuits related to the restraint system
- Check for other related airbag/passive restraint codes that may point to a common fault
- Perform wiggle test on seat wiring while monitoring live data for the switch
Signal parameters
- Switch type: typically a simple open/closed contact; output reported as switch state to restraint module
- Expected voltage: when supplied, reference/supply typically ~5 V or ignition/switched 12 V depending on vehicle; check OEM wiring diagram
- Closed (activated) resistance: near 0 Ω between switch terminals; open when released (high resistance/OL)
- Open circuit behavior: module reports missing signal or out‑of‑range when >10 kΩ or open
- Intermittent/unstable: fluctuating voltage or resistance indicates wiring or connector intermittent
Diagnostic algorithm
- Retrieve all restraint DTCs and record freeze frame/live data. Note whether code is current or historic.
- Follow manufacturer safety procedure for servicing restraint systems (disconnect battery negative and wait specified time to disable airbags before accessing connectors).
- Visually inspect the head restraint switch assembly and connector for damage, corrosion, moisture, or improper seating.
- Using the wiring diagram, identify switch supply, signal, and ground pins at switch and at the restraint control module.
- With ignition ON (and battery reconnected per safety procedure), monitor switch signal with a scan tool or multimeter while operating the head restraint. Look for expected change in voltage or resistance.
- Perform continuity/resistance check between switch terminals and control module pins with connectors disconnected. Repair any opens or shorts found.
- If wiring and connector are good, bench‑test or swap the known‑good switch (if available) or measure switch resistance while actuating. Replace switch if out of specification or intermittent.
- Inspect and repair/replace any damaged harness sections, pins or connectors. Apply dielectric grease if moisture was present.
- Clear codes and retest. If B106D returns and wiring/switch verify good, consider module diagnosis or reflashing per dealer procedures.
- After repair, perform a full system scan and verify no other restraint faults remain and that the system completes built‑in self‑tests.
Likely causes
- Connector pins corroded or pushed out at the switch under the seat
- Wiring chafed where harness passes through seat or body
- Switch failed electrically (stuck, intermittent contact)
- Module reporting erroneous data due to internal fault or firmware issue
- Blown fuse or poor power/ground at the circuit
Fault status
Status
Head retention switch circuit fault — open/short/intermittent signal detected by restraint control module.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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