B0156

Code

Generic B — Body

Body Control Module — Door Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 4 EN: 9 RU: 6

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Page language: EN

One or more door features not working (power windows, locks, mirror adjust, courtesy lights)
Intermittent or permanent door-related warning lamps/messages on dash
Multiple correlated communications codes present
Door status or lock/unlock events not reported to vehicle network
Symptoms may change with door position or when harness is flexed

Use a scan tool to read all related codes and attempt to communicate with the door module
Check vehicle battery voltage and fuses/relays for door module and BCM circuits
Visually inspect connectors at the door module, door jamb junction, and BCM for corrosion, bent pins, or water
Perform wiggle test of door harness while observing live data or watching for code set/clear
Measure CAN or LIN bus voltages at the BCM and door module connectors
Check termination resistance across CAN_H and CAN_L (approximately 60 Ω total)

CAN bus (typical): CAN_H ≈ 2.5 V and CAN_L ≈ 2.5 V in recessive state; dominant state shows a differential of ~1.5–3.5 V
CAN bus termination: roughly 60 Ω measured between CAN_H and CAN_L at a single point (two 120 Ω in parallel)
LIN bus (if used): idle at near battery voltage via pull-up; messages are voltage pulses to ground
Module power: supply voltage near battery voltage (12 V nominal) with no excessive voltage drop during operation
Ground: low resistance to chassis (typically
Open circuit or resistance much higher than expected indicates wiring break or poor connection

Connect a scan tool and record all codes and freeze-frame data. Attempt to communicate with the door module; note if it responds.
Check battery voltage and relevant fuses/relays. Recharge or replace battery if low before further testing.
Visually inspect connectors at the affected door module, the door jamb splice, and the BCM for corrosion, water, damaged pins, or loose terminals.
Perform a wiggle test of the door harness while monitoring live data or scanner communication status; look for intermittent changes or code reappearance.
Backprobe the communications lines at the door module and BCM. Verify proper idle voltages on CAN or LIN and measure termination resistance across CAN_H/CAN_L.
Check continuity and resistance of power and ground circuits from BCM to the door module. Repair any high-resistance joints, broken wires, or poor grounds.
If a short to battery or ground is suspected on the bus, isolate sections of the bus (disconnect modules) to locate the fault.
If wiring and connectors test good, swap or bench-test the door module if possible, or substitute a known-good module to confirm module failure.
If module replacement is required, ensure correct part number and perform any required programming, configuration, or relearn procedures.
Clear codes and road-test or cycle doors to confirm repair; recheck for return of B0156 or related codes.

Wiring damage at door hinge (most common source of intermittent open/short)
Connector corrosion or bent pins at door module or jamb connection
Failed door module electronics
Faulty ground or low battery/poor battery connection causing intermittent communication
Bus termination or short on CAN/LIN (less common than wiring in hinge)