B3125 on 2007-2013 GMC Sierra 1500 — Driver Door Only Unlock Circuit Malfunction
1 vehicles · 1 makes · $180-$500 repair
Most Reported On
B3125 is an OBD-II diagnostic trouble code meaning “Driver Door Only Unlock Circuit Malfunction.” B3125 is a body code, commonly defined on GM/Opel-family vehicles as a malfunction in the driver-door-only unlock circuit. The body control module provides voltage and ground to the door lock actuators to perform lock/unlock commands, and it sets this code when it detects a short to battery, short to ground, or open in the driver-door unlock control circuit. The most common symptom is inoperative power door locks for that function; it is a convenience fault, not a safety issue. This code is most commonly reported on 2007-2013 GMC Sierra 1500, with repair costs ranging from $180 to $500.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose B3125, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
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A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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BlueDriver Pro Bluetooth Scanner
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Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
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LAUNCH CRP123X OBD-II Scanner
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A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
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Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
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FAQ
What does B3125 mean?
B3125 stands for "Driver Door Only Unlock Circuit Malfunction." B3125 is a body code, commonly defined on GM/Opel-family vehicles as a malfunction in the driver-door-only unlock circuit. The body control module provides voltage and ground to the door lock actuators to perform lock/unlock commands, and it sets this code when it detects a short to battery, short to ground, or open in the driver-door unlock control circuit. The most common symptom is inoperative power door locks for that function; it is a convenience fault, not a safety issue.
What are the most common causes of B3125?
The most common causes of B3125 are: Short to battery or ground in the driver unlock circuit, Open circuit / broken wire (often at the door boot), Failed driver door lock actuator, Corroded or damaged door harness connector, Water intrusion into the door module/connector, Body control module output driver fault. The specific cause varies by vehicle.
How much does it cost to fix B3125?
Repair costs for B3125 range from $180 to $500, depending on the vehicle and root cause.
Which vehicles are affected by B3125?
Au7o has documented B3125 across 1 vehicle models from 1 manufacturers: GMC.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.