B1D47

Code

Generic B — Body

Body Control Module — Interior Lighting Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 15 EN: 13 RU: 15

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Page language: EN

Causes

Blown fuse protecting interior lights
Open circuit (broken wire, pushed-out connector, damaged bulb/LED)
Short to ground or battery (chafing, pinched wire, aftermarket accessory)
Corroded or loose ground connection
Failed lamp, LED module or LED driver
Faulty BCM output driver or internal electronics

Symptoms

One or more interior lights do not illuminate
Dome/map lights flicker or vary in brightness with vehicle load
Interior lights stuck ON or OFF unexpectedly
Battery drain when vehicle is parked (parasitic draw)
Instrument cluster message or warning related to interior lights
Inability to control brightness using dimmer control or occupant switches

What to check

Pull diagnostic trouble codes with an OEM-capable scanner and record freeze-frame data
Visually inspect interior lamps, sockets and connectors for corrosion, burned pins or water
Check fuses and fuseholder contacts for continuity and proper seating
Check for aftermarket wiring splices near interior lights, headliner, glove box and B-pillar
Measure voltage at the lamp connector with connector connected and disconnected
Verify ground integrity at lamp and BCM ground points (check for continuity to chassis)

Signal parameters

Supply voltage at BCM output / lamp feed: approximately battery voltage (11–14.5 V during cranking/normal operation)
Lamp connector voltage with switch ON: ~battery voltage (close to 12 V)
Lamp ground potential: ~0 V (verify
Dimming control (if PWM): duty cycle 0–100% (frequency typically 50–500 Hz depending on manufacturer)
Typical current per incandescent interior lamp: 0.5–3 A; per LED module: ~0.02–2 A depending on module; excessive current (>expected) suggests short or lamp fault
Open-circuit expected: infinite/OL continuity on circuit when lamp removed; short-to-ground: near 0 Ω between feed and ground

Diagnostic algorithm

Read and record all DTCs and freeze-frame data; note affected lamp circuits and any related communication codes.
Visually inspect affected lamps, sockets, connectors, BCM connector and fuse panel for damage, corrosion, or water.
Check fuses and fusible links for continuity; replace if blown and observe whether fuse blows again when circuit is energized.
Remove lamp/LED module and inspect. Test lamp on bench with known good 12 V supply (use appropriate resistor or current-limited supply for LEDs).
With connector disconnected, measure supply voltage at the harness connector with the lighting switch ON to confirm BCM output or fused feed voltage.
Measure continuity/resistance from lamp ground pin to chassis ground (
If dimming is used, monitor PWM signal at the BCM output with a scope or diagnostic tool while operating the dimmer; confirm expected frequency/duty and stable behavior.
Check for short-to-battery by measuring current when circuit is connected; if fuse blows, isolate sections of circuit (disconnect lamps/modules, unplug connectors) to locate short.
Inspect harness routing (headliner, pillars, glovebox) for chafed wires or pinched sections; repair with proper solder/heat-shrink or OEM splice connectors.
If wiring and lamps check good and BCM outputs do not command correctly, verify BCM power/ground and network communications; retest after restoring good power/ground.
Clear codes and test drive/operate lights to confirm repair. If BCM internal driver is confirmed failed and all wiring/lights are good, replace or reprogram BCM per manufacturer procedures.