B3125 on GMC
Driver Door Only Unlock Circuit Malfunction
B3125 on GMC vehicles indicates driver door only unlock circuit malfunction. Au7o has documented this code across 1 GMC model — most commonly on Sierra 1500. 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. Typical repair costs on GMC range from $180 to $500, depending on the specific model and root cause.
Common Causes of B3125
- •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
B3125 on GMC by Model
GMC Sierra 1500(1 issue)
- Power Door Lock Actuator Failure Causing Intermittent or Inoperative Locking2007-2013
GMT900 Sierra trucks are well known for failing door lock actuators, often starting with one door that unlocks weakly or only works intermittently before additional doors fail. Owners report the key fob cycling the locks while one or more doors remain stuck, requiring manual operation from inside. The issue is heavily documented across GM full-size truck forums and complaint records.
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View B3125 across all makes →Frequently Asked Questions
What does B3125 mean on GMC?▼
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. On GMC specifically, this code is documented across 1 model.
What causes B3125 on GMC vehicles?▼
Common causes on GMC: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix B3125 on a GMC?▼
Repair costs on GMC range from $180 to $500, depending on the specific model and root cause.
Which GMC models have B3125 documented?▼
Au7o has documented B3125 on 1 GMC model: Sierra 1500.