Code
B2602
HUMMER
B — Body
Daytime Running Lamp Circuit Low (BCM)
AI status
Completed
Completed
100%
Causes
- Burned out or faulty DRL lamp/bulb (open or high resistance)
- Poor or corroded lamp/ground/connector connection
- Open circuit (broken wire) or high resistance in DRL harness
- Short to ground or partial short in wiring or connector
- Blown fuse or fusible link supplying the DRL circuit
- Faulty DRL resistor/module (if used) or intermediate relay
Symptoms
- Daytime running lamps do not illuminate or are very dim
- DRL indicator or body lamp warning message on dash
- Front lamps work in other modes (parking/headlamps) but not DRL
- Intermittent DRL operation or changes with engine/vibration
- Related lighting circuits may show faults or behave abnormally
What to check
- Retrieve all stored DTCs and freeze-frame data; note operating conditions when code set
- Perform a visual inspection of DRL bulbs, sockets, wiring, connectors, and ground points for damage or corrosion
- Check related fuses and fusible links for continuity and correct rating
- Check battery and charging system voltage with engine off and running (nominal ~12.5 V off, ~13.5–14.5 V running)
- Backprobe the DRL lamp/socket while operating to measure supply voltage and ground continuity
- Perform a wiggle test of harness and connectors while observing DRL operation and monitoring for code recreation
Signal parameters
- Expected lamp supply voltage when DRL ON: approx. battery voltage under load (~11–14.5 V) at socket for standard bulbs
- LED DRLs: lower current draw (tens to hundreds of mA) and may be driven by BCM with PWM; voltage still near battery level when ON
- Open/low-voltage condition: measured voltage significantly below battery (for example
- Continuity to ground at lamp ground point: typically
- Typical incandescent DRL current: ~0.5–3 A per lamp (varies by vehicle/bulb); LEDs are much lower—consult service data
- BCM output may be PWM; expected frequency/duty documented in service manual—compare to specification
Diagnostic algorithm
- Confirm code: Connect scan tool, confirm B2602 and any related codes, record freeze-frame and repeat conditions.
- Visual inspection: Inspect DRL bulbs, sockets, wiring, and grounds for corrosion, damage, or loose connectors; inspect for aftermarket taps or resistors.
- Check fuses/relays: Verify continuity and correct fuses/relays for DRL circuit; replace if blown and recheck.
- Functional lamp test: With lamp removed or accessible, apply battery voltage to the lamp to verify it lights (or test known-good lamp).
- Measure at socket: Backprobe the socket with DRL commanded ON and measure supply voltage and ground. Note if voltage equals battery voltage or is low/absent.
- Check continuity: With power off, measure resistance from lamp socket positive to BCM output pin and lamp ground to chassis ground; repair any open/high resistance.
- Isolate load: Disconnect lamp and measure BCM output with scan tool commanding DRL ON. If output remains low with no load, suspect BCM output driver.
- Wiggle and retest: With the circuit energized, wiggle connectors and wiring to reproduce intermittent faults.
- BCM/software: If wiring and lamp check good, check for BCM technical service bulletins or reflash/recoding requirements; consider BCM replacement only after confirming output failure.
- Repair and verify: Repair wiring/replace bulbs/clean grounds/replace faulty module as required. Clear codes and verify DRL operation through multiple ignition cycles and test drive.
Likely causes
- Failed DRL bulb or LED module (most common)
- Corroded or loose connector/ground at lamp
- Open or damaged wiring to lamp socket
- Faulty BCM lamp driver or internal output transistor
- Blown fuse or damaged DRL module/relay
Fault status
Status
Daytime Running Lamp Circuit Low (BCM)
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
-
HUMMER: 2009
-
HUMMER: 2008
-
HUMMER: 2007
-
HUMMER: 2005
-
HUMMER: 2004
-
HUMMER: 2000
-
HUMMER: 1999
-
HUMMER: 1994
-
HUMMER: 1993
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email