B1428

Code

Other B — Body

Lamp Seat Belt Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 27 EN: 44 RU: 32

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Page language: EN

Seat belt warning lamp not illuminating during key-on or when seat belt is unbuckled
Warning lamp stuck on or flickering intermittently
Seat belt chime or reminders may not operate properly
Related body/module fault indicators or stored DTCs
Intermittent operation that changes with vibration/wiring position

Retrieve freeze-frame and accompanying codes with a scan tool; note lamp command/status
Perform a visual inspection of the lamp, socket and wiring for damage or corrosion
Check fuses related to instrument cluster/BCM
Operate the instrument cluster self-test to confirm lamp function
With a multimeter, check for supply voltage and ground at the lamp connector while commanding lamp on/off
Check continuity between the lamp connector and the control module connector

Lamp supply voltage with lamp ON: ~11–14 V (if the circuit is power-switched) or ground switched to ~0 V depending on vehicle design
Lamp voltage with lamp OFF: ~0 V (or open) or battery voltage depending on switching topology
Expected current: incandescent bulbs typically 100–500 mA; LED indicator 10–100 mA. Compare to known-good specification for the vehicle
Connector/ground continuity to chassis: near 0 ohms (a few ohms maximum)
Open-circuit condition: very high resistance / infinite ohms between lamp and module

Read and record all stored codes and live data; note whether the module is commanding the lamp ON during tests.
Perform the instrument cluster/BCM lamp self-test. If the lamp illuminates on self-test, suspect wiring, connectors or belt buckle sensors; if not, suspect the lamp or driver.
Visually inspect lamp, socket and wiring for damage, corrosion or loose connectors. Repair or clean as needed.
Check related fuses and replace if blown. Re-test.
Remove lamp (or access LED board) and test lamp directly by applying 12 V ground/power as appropriate to confirm lamp health.
With a multimeter, backprobe the lamp connector. Command the lamp ON with a scan tool and verify expected supply or ground signal (refer to vehicle-specific topology).
If no command signal reaches the lamp, trace continuity from the lamp connector back to the module. Repair any open/shorted wiring or damaged pins.
If wiring and lamp are good but no proper signal, test the module output for shorts to battery or ground and inspect for water/damage. Replace or repair module only after verifying wiring.
After repairs, clear codes, perform a full system test and verify proper lamp operation during key-on and fault conditions.
If fault persists after wiring and lamp replacement, consult vehicle manufacturer wiring diagrams and consider module bench testing or replacement.