Code
B3717
HUMMER
B — Body
Left Front Door Module Communication - No Response
Views:
UK: 15
EN: 19
RU: 12
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the door harness (including at the hinge/jamb area)
- Poor power or ground to the left front door module
- Corroded or loose connector at the module or door jamb
- CAN/LIN bus fault or wiring damage
- Module failure (internal electronics)
- Body Control Module (BCM) or gateway not addressing the module
Symptoms
- Left front door functions not working: power window, door lock/unlock, mirror adjustments, courtesy lamps
- Driver information messages or chimes indicating module communication fault
- Other modules report loss of communication with left front door module
- Intermittent operation—features work sometimes when door is fully opened/closed or harness flexed
- Possible blown fuses or erratic accessories behavior
What to check
- Retrieve stored and pending DTCs with a capable scan tool and note freeze frame and events
- Verify ignition/key-on states and attempt to communicate with the LFD module using scan tool
- Visually inspect door jamb harness for damage where it flexes at the hinge; look for broken wires or pinched areas
- Inspect connector for corrosion, bent pins, or water intrusion at module and at the door switch/wing connector
- Verify fuses and power distribution feeding the door module (measure battery voltage at fuse and module power pin)
- Check continuity and voltage of module ground(s) — confirm good low-resistance ground to chassis
Signal parameters
- CAN High (recessive): ~2.5 to 3.5 V typical; CAN Low (recessive): ~1.5 to 2.5 V typical
- Dominant CAN state: differential voltage ≈2.0 V (CANH rises, CANL falls); recessive differential ≈0 V
- If module uses LIN: LIN idle ≈ battery voltage when idle and pulled low during transmission (varies by vehicle)
- Expected bus speed: door modules commonly on medium/low speed CAN or HS-CAN depending on model (confirm with factory data)
- When key ON and module awake: module should respond to addressed diagnostics and appear on network (no-response indicates bus or module issue)
Diagnostic algorithm
- Connect a factory-level or capable aftermarket scan tool. Read and record all codes and network status. Attempt to communicate with the Left Front Door Module.
- If code is active, check for related U-codes (network/bus faults) to determine if problem is isolated to the door module or bus-wide.
- Inspect fuses and measure battery voltage at the power pin of the LFD module connector with ignition ON. Replace any blown fuses.
- Inspect and probe the door harness at the hinge/jamb for broken wires, exposed conductors, or crushed sections. Repair any damaged wiring.
- Backprobe module connector: verify battery feed(s), accessory feed(s), and ground(s) have appropriate voltages (battery voltage at power;
- Probe CANH and CANL at module connector with multimeter/oscilloscope: confirm idle voltages and that differential changes during communication. If bus is stuck dominant or shorted, isolate wiring to find short.
- Perform an intermittent/wiggle test while monitoring network traffic to replicate the fault. Pay attention to connector position in door jamb.
- Disconnect the door module and inspect pins for corrosion or damage. Clean or repair connector as needed. Reconnect and retest communication.
- If harness and power/ground are good but no communication, try to wake the module using a capable scan tool (force awake) or by cycling ignition and opening the door.
- If module still does not respond and wiring is verified good, consider replacing the door module. Ensure correct part number and reprogram/configure per factory procedures after installation.
- After repair or replacement, clear codes and verify normal operation of door functions and that the module reports on the network with no recurrence of the B3717 code.
Likely causes
- Broken or chafed wires in the door harness where it flexes at the hinge/jamb
- Blown or loose fuse supplying the door module
- High resistance ground at door module mounting point
- Corroded pins in the door module connector from moisture
- CAN bus shorted to battery or ground on the door side
- Module failed after impact or long-term exposure to moisture
Fault status
Status
No response from Left Front Door Module on vehicle communication network — communication fault (B3717).
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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