Code
B3801
HUMMER
B — Body
Passenger Compartment Lamp Request Circuit
Views:
UK: 21
EN: 28
RU: 22
AI status
Completed
Completed
100%
Causes
- Blown fuse or faulty relay feeding the passenger compartment lamp circuit
- Open or shorted wiring between lamp(s) and the BCM or switch
- Corroded or loose connector at lamp, switch, ground, or BCM
- Faulty passenger compartment lamp switch or lamp assembly
- Failed bulb or shorted lamp socket
- Faulty BCM or unit controlling the lamp request
Symptoms
- Passenger-side interior lamp does not come on when requested
- Lamp stays on and does not turn off or is intermittent
- Interior light warning or dome light fuse blows repeatedly
- Battery drain when vehicle is off
- Related lighting functions controlled by the BCM operate incorrectly
What to check
- Scan for stored and pending codes; record freeze frame and related codes
- Visually inspect fuses and relays for the interior lighting circuit
- Inspect lamp bulb(s) and socket(s) for damage, corrosion, or burnt contacts
- Visually inspect wiring and connectors from the lamp to the BCM for damage or corrosion
- Backprobe connector at the lamp and at the BCM while operating the switch to verify signal/power/ground
- Check for aftermarket wiring tied into the lamp circuit
Signal parameters
- Expected lamp feed voltage: ~12 V (battery) when lamp request is on; 0 V (or open) when off (or switched ground depending on design)
- Control/logic inputs to BCM: 0–5 V for logic-level switches on some modules (verify with service data)
- Typical passenger dome lamp current draw: 0.1–2 A depending on bulb type (incandescent higher; LED lower)
- Connector/terminal resistance: near 0 ohms between chassis ground points; continuity from lamp socket to BCM when circuit closed
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data with a scan tool; review vehicle-specific service information and wiring diagrams.
- Visually inspect fuse(s) and relay(s) for the dome/interior lighting circuit; replace if blown and retest. If fuse blows again, proceed to wiring checks.
- Inspect the passenger lamp assembly: remove bulb and socket, check for corrosion, shorted contacts, or melted insulation. Replace bulb or repair socket as needed.
- With switch operated, backprobe the lamp connector: verify presence/absence of feed voltage or switched ground per wiring diagram. Note readings with lamp removed and installed.
- Check continuity and resistance of the wiring between the lamp and the BCM/switch. Repair any open or high-resistance circuits. Check grounds for low resistance to chassis.
- Inspect and test the passenger lamp switch (or door jamb switch) for proper operation and continuity. Replace if faulty.
- If wiring and lamp/switch check good, monitor BCM inputs/outputs with a scan tool while operating the light request; compare actual values to expected signal parameters.
- If BCM outputs are incorrect and wiring is confirmed good, consider BCM replacement or reprogramming per manufacturer procedure.
- Clear codes and retest full system operation, including door-open/close and remote/auto functions. Confirm code does not return.
Likely causes
- Loose/corroded connector at the passenger lamp or ground
- Damaged wiring harness (pinched, chafed) causing intermittent open or short
- Failed bulb or lamp socket causing short to ground
- BCM output or input for lamp request has failed
Fault status
Status
Passenger Compartment Lamp Request Circuit - The control module detected an open, short, or out-of-range signal on the passenger interior lamp request circuit. Lamp may not operate correctly or may cause battery drain.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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