U0200

Code

Generic U — Network/User

Lost Communication With Door Control Module B

Brand: Generic

Type: U — Network/User

Views: UK: 24 EN: 60 RU: 37

AI status

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Page language: EN

Causes

Open or short in CAN high/low wiring to Door Control Module B
Loss of module power (blown fuse, supply circuit open)
Bad or missing ground at the door module
Failed Door Control Module B (internal electronics or software fault)
Corroded or damaged connector/pins (water intrusion, wear)
CAN bus termination or wiring fault causing network failure

Symptoms

Door-related features (locks, windows, mirror folding, courtesy lights) nonfunctional or intermittent
Warning or message on dash indicating module or communication fault
Related diagnostic trouble codes (other U-codes) present
Remote key/unlock or door sensor functions inconsistent
Modules that rely on door module data show erroneous status (e.g., lighting, alarm)

What to check

Use a scan tool to confirm U0200 and check if Door Control Module B is listed/present on the network
Check battery voltage (vehicle should be at nominal voltage during tests)
Verify fuses and power feeds to the door module (ignition-switched and constant supplies)
Verify ground connections at module and nearby chassis grounds
Visually inspect module connectors and harness, especially at door hinge areas, for damage or corrosion
Check for other U-codes on networked modules (may indicate wider CAN issue)

Signal parameters

CAN bus nominal idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V; differential when active ≈ 2.5 V difference
Expected bus termination: ~60 ohms between CAN_H and CAN_L (two 120 Ω in parallel)
Door module messages usually present at low frequencies (typical 1–20 Hz for state, higher for commands) — verify presence of periodic frames
Typical signals from module: door lock/unlock commands, door ajar status, window/mirror control commands, courtesy lamp status
Message absence (no frames with the door module ID) is the key symptom on the bus

Diagnostic algorithm

Connect a diagnostic scan tool. Confirm U0200 is active and note any related codes or freeze frame data.
Verify battery voltage and check fuses/power supplies feeding Door Control Module B. Repair any open fuses or supply faults.
Inspect the module connector and wiring, focusing on door hinge flex areas. Repair visible damage or corrosion.
Backprobe the module power and ground pins to confirm proper voltages and a solid ground with engine off and key on.
Check for module presence on the network via scan tool. If module not present, capture CAN bus traffic using scope or bus analyzer to confirm absence of frames from that node.
Measure CAN_H and CAN_L at the module connector: check idle voltages, differential during activity, and total bus resistance. Repair shorts or open conductors and restore proper termination.

Likely causes

Connector corrosion or water intrusion at door module
Blown fuse or open supply/ignition feed to module
Broken CAN H or CAN L conductor in door harness (common at hinge area)
Missing ground at module chassis/ground strap
Failed door module hardware (internal failure)
High CAN bus load or short to battery/ground on CAN line

Fault status

⚠️ Status

Lost Communication With Door Control Module B — module not responding on vehicle network (CAN). Verify power/ground, connectors, and CAN wiring before replacing module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-2 hours