B0171

Code

Generic B — Body

Driver Door Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 19 EN: 31 RU: 18

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring in the driver door harness (flex/hinge area)
Corroded or loose connector pins at the door module or BCM
Water intrusion into door connectors or the module
Faulty driver door module
Blown fuse or loss of module supply/ground
High or low battery voltage or intermittent supply

Symptoms

Driver door functions inoperative or intermittent (power window, power lock, mirror, seat memory if applicable)
Central locking may not respond from driver door switch
Interior/door courtesy light behavior abnormal or inoperative
Door-related switches intermittently not recognized
DTC B0171 stored and possibly other communication/door module codes
Features that rely on DDM messages behave erratically or not at all

What to check

Connect a scan tool and verify B0171; note freeze frame and related codes
Check battery voltage and charge state; verify good battery ground and chassis grounds
Inspect fuses and fusible links for door module circuits
Visually inspect door harness at hinge for chafing, broken wires, or exposed conductors
Inspect connectors at door module and BCM for corrosion, bent pins, or water intrusion
Perform a wiggle test of the door harness while watching live data/communication status on a scanner

Signal parameters

CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both converge near mid-supply)
CAN bus dominant: CAN_H ≈ 3.5–4.0 V, CAN_L ≈ 1.0–1.5 V (voltage difference ~2 V)
Total CAN bus termination resistance ≈ 60 ohms measured across CAN_H and CAN_L with ignition off
LIN bus idle: roughly battery voltage via pull-up; dominant state pulled toward ground (~0 V)
Module supply: DDM battery feed ≈ 12 V with ignition/accessory on; ground < 1 ohm to chassis

Diagnostic algorithm

Retrieve and record all stored codes and freeze-frame data. Note whether the code is current or historic. Clear codes and attempt to reproduce.
Verify vehicle battery voltage and main grounds. Low battery or poor ground can produce communication faults.
Inspect door hinge flex section and all door harness routing for visible damage, pinched or broken wires. Repair any damaged wiring using proper splice and sealing methods.
Disconnect door module and inspect connector pins for corrosion, bent pins, or pushed-out pins. Clean or repair as required.
With a DVOM, measure DDM supply voltage and ground at the module connector. Confirm ignition-switched 12 V present where required.
Check the CAN/LIN bus: measure idle voltages on CAN_H and CAN_L; measure termination resistance across the bus (~60 ohms). Use an oscilloscope if available to view message activity and noise.
Perform a wiggle test of the door harness and connectors while monitoring live data or communication status. If the fault is triggered by movement, focus repair at the hinge flex area.
If wiring and connectors check good, swap or bench-test the driver door module per manufacturer procedure or substitute with a known-good module if available. Reflash or reprogram module if software updates are required.
If communications still fail after replacing the DDM, check BCM and other network nodes for faults or bus contention; inspect termination resistors and bus topology.
After repair, clear codes and verify repair by exercising door functions and re-checking for returned codes over an appropriate drive cycle.

Likely causes

Wiring damage at the door hinge flex area (most common on vehicles with repeated door movement)
Loose/corroded connector at DDM or toe board connector
Intermittent ground or 12 V supply to the door module
Door module internal electronics failing
CAN bus short to battery or ground, or missing termination resistor
Water-damaged door module or connector

Fault status

⚠️ Status

Stored when the body control system detects missing, invalid, or intermittent communication from the driver door module on the vehicle communication bus (CAN/LIN). May be set as intermittent or permanent depending on detection count and conditions.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours