Code
B1A37
LAND ROVER
B — Body
Left curtain control deployment bag 2 of air - short walk of ignition circuit Control deployment
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EN: 4
RU: 2
AI status
Completed
Completed
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Causes
- Damaged or chafed wiring in left curtain deployment (bag 2) circuit
- Corroded, loose or pushed-out connector at the curtain airbag, curtain module or airbag control unit (ACM)
- Short to ignition or vehicle supply on the bag 2 wiring (fused or switched 12V feed contacting squib circuit)
- Faulty curtain airbag squib (internal short)
- Faulty airbag control module or internal driver fault
- Previous repair or after-market fitting that disturbed SRS wiring or connectors
Symptoms
- SRS/Airbag warning lamp illuminated continuously
- Possible freeze-frame data showing left curtain (bag 2) circuit fault
- SRS system may disable specific deployment for affected bag
- No other driveability symptoms (vehicle otherwise runs normally)
What to check
- Read SRS module live data and stored fault details with a compatible scan tool (record code present, fault counters, freeze-frame)
- Confirm vehicle-specific safety procedure: disconnect battery negative and wait manufacturer-specified time (commonly ~90 seconds) before touching SRS circuits
- Visually inspect left roof rail/A-pillar wiring harness, connectors and curtain airbag connector for damage, corrosion, or pushed-out pins
- Check connector retention and presence of terminal seals and correct routing (look for recent repair evidence)
- Measure squib circuit resistance at the curtain module connector with battery disconnected (compare to manufacturer spec)
- Check for short to ignition/supply by measuring resistance between squib circuit and fused/switched 12V feed and to ground (battery disconnected)
Signal parameters
- Expected pyrotechnic squib resistance: typically ~2–6 ohms (manufacturer specific) — consult OEM data
- Open circuit: very high resistance (>>10 ohms or OL)
- Short to ground/supply: near 0–1 ohm to ground or to 12V rail (indicates short)
- Module supply voltage at ACM connector (with ignition ON) should be ~11–14 V (measure at module power pins per wiring diagram)
- Continuity between squib circuit and vehicle body ground should be high unless specified by wiring routings (shorts present when very low resistance)
Diagnostic algorithm
- Connect an OEM-capable SRS scan tool, read and record all airbag DTCs and freeze-frame data. Do not clear codes yet.
- Follow Land Rover safety procedure: disconnect battery negative and wait manufacturer-specified time before any SRS wiring or connector work.
- Visually inspect left curtain airbag, harness along roof rail/A-pillar, connectors at the curtain module and ACM for damage, corrosion, bent pins, or signs of previous repair.
- With battery disconnected, measure resistance of the left curtain bag 2 squib between the two squib terminals at the curtain module connector. Compare to OEM spec (typical squib ≈2–6 Ω). Note: a very low value (~0–1 Ω) suggests short; an open/OL suggests open circuit.
- With battery disconnected, check resistance from squib circuit to vehicle 12V ignition feed and to chassis ground to identify unwanted shorts to supply or ground.
- If wiring appears intact, disconnect the curtain module and measure squib resistance at the harness side to isolate module vs. harness. If harness shows correct resistance and module side is abnormal, suspect module or squib.
- Repair identified damaged wiring or corroded connectors using approved SRS terminals and seals; replace connector shells or pigtails only per OEM instructions.
- If squib internal short suspected, replace the curtain airbag (do not attempt to repair squib). If module driver suspected after harness isolation, follow OEM guidance for module replacement/calibration.
- Reconnect, clear codes, and perform required SRS system checks and scans. Verify lamp extinguishes and no new B1A37 returns. Re-check scan tool live data.
- After any component replacement, perform manufacturer-required SRS system initialization or seat/occupant classification checks if applicable.
Likely causes
- Wiring chafe near A-pillar/roof rail where harness is routed causing short to ignition feed
- Connector pin corrosion or bent pin at curtain module or ACM
- Squib internal short due to moisture ingress or age
- Incorrect re-assembly after headliner/service work
Fault status
Status
Airbag control module detected a short condition in left curtain deployment circuit (bag 2) — abnormal continuity/voltage on the deployment/squib wiring or module driver.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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