Code
B2473
HUMMER
B — Body
High Beam Fault
AI status
Completed
Completed
100%
Causes
- Burned-out high-beam bulb filament
- Corroded, loose or damaged headlamp connector or wiring
- Blown fuse or faulty headlamp relay
- Poor ground at the headlamp or chassis
- Faulty multifunction/headlight switch
- Body Control Module (BCM) or headlamp control module fault or software issue
Symptoms
- High beams do not illuminate when selected
- One side high beam inoperative while other side works
- High-beam indicator on dash does not match lamp state (stays on or off incorrectly)
- Intermittent high-beam operation or flickering
- Diagnostic warning or message displayed on the instrument cluster
What to check
- Use a scan tool to read stored and pending DTCs; record freeze-frame data and any related codes
- Visually inspect the high-beam bulbs and headlamp lenses for moisture, damage, or discoloration
- Inspect fuses and relays for the headlamp/high-beam circuits
- Visually inspect harness and connectors at each headlamp for corrosion, bent pins, or water ingress
- Check chassis ground(s) for the headlamp circuit and clean/tighten as needed
- With headlamps on, measure voltage at the high-beam connector (back-probe) and at the fuse/relay output
Signal parameters
- Battery supply voltage at fuse/relay: ~11–14.5 V with engine off/run
- Expected high-beam lamp current (typical halogen 55 W): ~3–6 A when illuminated (varies by lamp type)
- Control signal to lamp: either battery voltage (switched power) or switched ground depending on design — should change state when high beams are commanded
- Connector pin resistance: continuity near 0 Ω for power/ground conductors (no open circuit)
- CAN/BUS messages: high-beam command should be present on vehicle data bus when switch is activated (verify with OEM scan tool)
Diagnostic algorithm
- Verify symptom: note whether lamp(s) fail, are stuck on, or flicker; confirm operator reports and instrument cluster indications.
- Scan all modules with a factory-level scan tool; document B2473 and any additional related codes and freeze-frame data.
- Visually inspect headlamp assemblies, bulbs, connectors, harness routing, and grounds for obvious damage or corrosion; repair as needed.
- Check fuses and swap or bench-test the headlamp relay (or substitute known-good relay) while monitoring lamp behavior.
- With a voltmeter, back-probe the high-beam connector at the lamp with high beams commanded: verify battery voltage at supply and good ground. If no supply, trace back to relay/fuse/BCM output.
- If lamp supply voltage is present but lamp does not light, replace bulb or test lamp on a bench power source. If lamp works, problem is upstream.
- If lamp does not receive correct control voltage, test continuity between lamp connector and BCM/relay; repair any opens or shorts. Perform wiggle tests to reveal intermittent faults.
- Check BCM or headlamp control module outputs and parameter values with factory scan tool; perform output tests if supported. Reprogram or replace module only after validating wiring and components are good.
- After repair, clear codes, run self-tests, and verify correct operation of high beams and that B2473 does not return. Road-test and re-inspect for intermittent faults.
- If issue persists and wiring and components are confirmed good, consult service information for module-specific diagnostics, TSBs, or software updates.
Likely causes
- Blown or failed high-beam bulb(s)
- Poor ground or corroded connector at headlamp
- Faulty headlamp relay or blown fuse
- BCM output circuit fault or internal module error
Fault status
Status
High Beam Fault detected. High-beam lamps may not operate correctly. Service required.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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