Code
B3152
HUMMER
B — Body
Left Front Lock Switch Circuit Low
AI status
Completed
Completed
100%
Causes
- Short to ground in left front lock switch wiring
- Open or damaged wiring/connector between switch and BCM/door module
- Corroded or loose connector pins at the switch or module
- Failed left front door lock switch
- Failed BCM/door control module or internal driver fault
- Water intrusion or contamination at switch/connector
Symptoms
- Left front door lock/unlock switch inoperative or intermittent
- Door lock operation from other switches or remote may be affected or behave oddly
- DTC B3152 stored in BCM/door module and may trigger a warning or disable local control
- Occasional fuse issues or parasitic draw in severe short cases
What to check
- Read stored DTCs and freeze-frame data with a scan tool; note any companion codes
- Perform a visual inspection of the left front door wiring harness, connector and switch for damage, corrosion, or water ingress
- With ignition ON, backprobe the switch connector and measure for reference voltage and signal changes while operating the switch
- Check continuity between the switch signal pin and the BCM/door module pin with connectors disconnected (wiring harness disconnected at both ends)
- Check for short to ground on the switch signal circuit (measure resistance to ground)
- Inspect for aftermarket alarm or remote lock wiring that may tap the circuit
Signal parameters
- Reference supply: approximately battery voltage (~12 V) with ignition ON (varies by vehicle)
- Switch signal: circuit should toggle between near 0 V (ground) and a higher voltage (close to reference) when operated, depending on switch wiring type
- Closed switch continuity: near 0 ohms (low resistance) across the switch contacts
- Open switch resistance: high (kΩ range) when not actuated
Diagnostic algorithm
- Verify DTC: connect a scan tool, record B3152 and any related codes, and clear the code to see if it returns.
- Visual inspection: open the left front door, inspect switch, wiring, grommet at the door hinge, and connector for corrosion, damage or water.
- Backprobe connector: with ignition ON, backprobe the switch connector. Verify reference voltage at the supply pin and observe the switch signal while operating the lock/unlock switch.
- Short/ground check: with ignition OFF, measure resistance from the switch signal pin to chassis ground. A low resistance suggests a short to ground.
- Continuity check: disconnect connectors at the switch and at the BCM/door module. Check continuity between the two connector pins to confirm no open circuit and note any high resistance.
- Wiggle test: with the connector connected and backprobed, flex the door harness through its travel range while observing the signal for intermittent drops or shorts.
- Isolate component: if wiring checks good, test/replace the left front door lock switch and retest.
- Module check: if switch and wiring are good and code persists, perform BCM/door module diagnostics per manufacturer procedures (may require module bench test or reprogramming).
- Repair and verify: repair/replace faulty wiring, connector, or switch; clear codes and verify repair by operating the lock and rescanning for codes.
Likely causes
- Corroded/loose connector at left front door lock switch (common in door harnesses)
- Damaged wiring in the door harness (pinched by hinge or chafed)
- Failed left front lock switch
- Short to ground in the switch harness
Fault status
Status
BCM detected low voltage/short-to-ground on left front door lock switch circuit (B3152). Repair wiring or switch and retest. If wiring and switch are good, suspect module fault.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Repair manuals
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138
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