Code
B1128
LAND ROVER
B — Body
Driver's side - control of the activation of the side inflatable curtain
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UK: 4
EN: 14
RU: 5
AI status
Completed
Completed
100%
Causes
- Open, short to ground or short to battery in the side curtain squib/activation circuit
- Corroded, loose or damaged connector(s) at the curtain module, roof harness or door jamb
- Water ingress or physical damage to the roof/door harness
- Faulty side curtain module or impact/crash sensor
- Faulty occupant sensing module or SRS control module (PCM/ECU communication error)
- Low or intermittent battery/vehicle supply voltage or poor ground
Symptoms
- SRS / airbag warning light illuminated or flashing on instrument cluster
- Possible disablement of driver-side side curtain airbag (no deployment if needed)
- Other SRS related warnings or reduced airbag readiness messages
- Stored DTC(s) and freeze frame data in SRS control module
What to check
- Read and record all SRS-related codes and freeze frame data with a capable scan tool
- Check battery voltage and charging system; ensure stable 12V supply
- Visually inspect wiring and connectors along the roof rail, A-pillar and door jamb for damage, corrosion or water ingress
- Inspect curtain module connector(s) and mounting for corrosion or loose pins
- Check for related or concurrent codes (other B1xxx or U0xxx codes) that indicate communication or module faults
- Confirm proper ground continuity at SRS module and chassis ground points
Signal parameters
- Supply voltage to SRS / curtain module: ~12 V (vehicle battery voltage) with ignition on — consult OEM spec
- Communication bus signals (CAN/LIN): differential CAN signals toggling, or LIN ~0–12 V depending on network — check with scope/scan tool
- Curtain squib circuit resistance: typically very low (single-digit ohms); consult manufacturer specification before measuring
- Open-circuit vs short indication: infinite/very high resistance indicates open; near-zero or short-to-power/ground indicates short (confirm with service manual values)
Diagnostic algorithm
- Use an OEM-capable scan tool to read and log B1128 and any other stored SRS codes and freeze frame data.
- Verify battery voltage and condition. Recharge or replace battery if voltage is low; retest code status.
- Visually inspect the roof-lining, A-pillar, door jamb and connector areas for damaged wiring, chafing, corrosion or water ingress. Pay attention to areas where harness runs into doors and roof.
- With ignition off and following SRS safety procedures (disconnect battery and wait the manufacturer-specified time before working on SRS), inspect and reseat the driver-side curtain connectors and SRS module connectors. Look for bent pins, corrosion or moisture.
- Perform a continuity/resistance check of the curtain squib circuit back to the SRS module per the workshop manual. Do not attempt to fire or energize the squib. Compare values to OEM specs; if out of range, isolate the fault to wiring, connector or squib.
- Check module power and ground circuits for proper voltage and good ground continuity. Repair any poor grounds or power faults.
- If wiring and connectors are good but fault remains, check communication lines (CAN/LIN) for activity with a scope or scan tool and verify no lost-comm codes. Address communication issues as required.
- If possible, clear codes and perform a wiggle test of the harness/connector while monitoring live data to see if the code returns (helps find intermittent faults).
- If fault persists and wiring checks out, follow OEM diagnostic flow for module replacement or sensor/squib replacement. After any repair, clear codes and verify system readiness and that the SRS light does not return.
- Safety note: Always follow the vehicle manufacturer’s SRS service procedures. Disconnect battery and wait the required time before handling airbag components; avoid using ohmmeters to attempt to fire squibs and do not connect a battery directly to squib circuits.
Likely causes
- Damaged wiring in roof lining/door area (common wear point)
- Corroded connector at curtain squib or module (often due to water ingress)
- Failed curtain squib or side curtain module
- Poor ground at SRS module or body grounding point
- Module communication failure (CAN/LIN) between SRS and airbag module
Fault status
Status
SRS fault: driver-side side-curtain deployment control circuit fault detected. SRS/airbag warning illuminated; curtain deployment may be inhibited until repaired.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
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