B1233

Code

LAND ROVER B — Body

Glass break sensor failure

Brand: LAND ROVER

Type: B — Body

Views: UK: 21 EN: 37 RU: 23

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Page language: EN

Causes

Failed or degraded glass break sensor (piezo or microphone element)
Open, short or intermittent wiring between sensor and control module
Corroded or loose connector(s)
Blown fuse or loss of sensor power/ground
Water ingress or physical damage to sensor
Faulty body control module (BCM) input or software fault

Symptoms

Alarm does not trigger when glass is struck or broken
False alarms or random alarm triggering
Warning light or message about intrusion/glass break sensor
Diagnostic trouble code B1233 stored; related security/BCM faults present
Glass break sensor indicator (if fitted) inactive or behaves abnormally

What to check

Read and record stored DTCs and freeze frame with a capable scan tool; check for related codes (BCM, CAN bus)
Visual inspection of glass break sensor location for physical damage or water ingress
Inspect connectors for corrosion, bent pins, or moisture; reseat connectors
Check relevant fuse(s) and fusible links for continuity
Verify battery voltage at key-on and sensor harness power pin (nominal ~11–14 V)
Measure continuity/ resistance of signal and ground circuits to the BCM

Signal parameters

Sensor power: nominal vehicle battery 12 V (expected ~11–14 V at key on/run)
Ground: low resistance path to chassis/BCM ground (
Sensor output: typically an analog pulse or voltage/frequency change on impact (idle ~small offset, event = transient pulse)
Expected event signal: short-duration pulses or high-frequency content when glass is struck (varies by sensor type)
Communications: BCM may report sensor status via CAN messages (glass_break_status / event_count)
Note: exact voltages/frequencies are manufacturer-specific; consult Land Rover technical data for precise values

Diagnostic algorithm

Connect an appropriate diagnostic scan tool; record DTC B1233 and any related codes. Clear codes and attempt to reproduce.
Inspect sensor and harness visually for damage, corrosion, moisture, or signs of recent glass replacement. Repair any obvious issues.
Check fuses and power supply to sensor circuit. Repair/replace fuse if blown and investigate cause of failure.
Backprobe power and ground pins at the sensor connector. Verify stable supply voltage and good ground with ignition on.
With a scope or multimeter capable of capturing transients, monitor the sensor output while gently tapping the glass near the sensor to confirm output pulses. If no response, suspect sensor or wiring.
Check continuity and resistance between the sensor output and the corresponding BCM input pin. Repair any opens or shorts.
Inspect/repair any splices or harness sections routed through doors/pillars where chafe occurs. Replace damaged wiring as required.
Verify BCM receives the sensor signal or CAN messages. If BCM does not see the input but wiring and sensor test good, consider BCM fault or reflash of module software.
If wiring and module OK, replace sensor and retest. After replacement, perform any required calibration or teach-in procedure per Land Rover service manual.
After repairs, clear codes and perform final verification: confirm alarm behavior and that DTC does not return during road/test environment.

Likely causes

Sensor element failure (most common)
Connector corrosion or poor terminal contact at sensor or BCM
Wiring harness chafe causing intermittent short to ground or open circuit
Power/ground fault (fuse, splice, or body ground)
Module communication or configuration error after service/replace

Fault status

⚠️ Status

Glass break sensor circuit malfunction detected. The body control module has logged a failure in the glass break sensor input—this may disable glass-break alarm detection or cause false alarms until repaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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