Code
U0222
MERCEDES-BENZ
U — Network/User
Lost Communication with Door Window Motor A
Views:
UK: 15
EN: 25
RU: 20
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the door harness (flex/hinge area)
- Corroded, pushed-out or damaged connector pins at the door harness or motor connector
- Blown fuse or faulty relay supplying motor/module power
- Poor or missing ground at the motor or door control module
- Failed window motor or integrated motor control (regulator assembly)
- Faulty door control module or vehicle body control module (BCM)
Symptoms
- Affected door window does not operate or operates intermittently
- No response when using door switch or remote window controls for that door
- Additional U-codes or module communication faults logged in vehicle network
- Humming or no movement from motor when command is given (motor may draw abnormal current)
- Other networked convenience functions on same door may be affected
What to check
- Read all stored and pending codes with a capable scan tool; note freeze-frame and event counters
- Attempt to operate window while monitoring live data for the door/window module and motor status
- Inspect fuses and relays for the power circuit to the door/window motor and door module
- Visually inspect door harness, hinge flex section and motor connector for damage, corrosion, bent pins or water ingress
- Check battery voltage and system ground quality before performing low-voltage tests
- Measure power and ground at the window motor connector while operating the switch
Signal parameters
- Battery supply voltage at motor connector while operating: typically ~11–15 V (engine off/on as applicable)
- Ground continuity to chassis ground: near 0 Ω
- Motor winding resistance (static): low ohms (typical range varies by motor; often
- Motor current draw while running: normally up to several amps; excessive current indicates mechanical bind or short
- Communication bus idle voltages: CAN high/low or LIN nominal idle voltages (measure with scope/multimeter)
- Presence of periodic communication frames and module responses for the door/window motor ID on the network (scan tool live-data)
Diagnostic algorithm
- Connect a diagnostic scan tool and record all U-codes and related network errors. Note whether code is permanent or pending and whether other modules report network faults.
- Clear the code and attempt an operation to reproduce. Observe freeze-frame and live-data while operating the affected window.
- Inspect fuses/relays for the circuit that feeds the door window motor and door control module; replace suspect fuses and re-test.
- Visually inspect the door harness, especially the flex/hinge area and motor connector for chafing, broken wires, corrosion or pin damage. Repair any damage found.
- With ignition on, measure battery voltage at the motor power terminal and verify good ground at motor housing while operating the switch. If power/ground missing or intermittent, trace and repair wiring to source.
- Monitor communication lines (CAN or LIN) with a scan tool/oscilloscope while commanding the window. Verify the module transmits/receives expected frames or whether bus is silent/bus-off.
- Perform a wiggle test of the harness while observing live-data or operating the window to find intermittent opens/shorts.
- If power/ground and bus are present but motor does not respond, measure motor winding resistance and perform a bench/bench-run test (remove motor) to confirm motor/function. Replace motor/regulator if failed.
- If motor and wiring check OK, check/reprogram/replace door control module or BCM as directed by manufacturer service information; ensure correct coding and software level after replacement.
- After repair, clear codes, cycle ignition, and verify proper operation and that communication remains stable. Road-test and re-check for reoccurrence.
Likely causes
- Wiring damage in door jamb flex harness (most common on doors that move frequently)
- Corroded connector pins at the motor or door harness
- Failed window motor or internal motor control electronics
- Blown fuse or intermittent power/ground to the motor/module
- Communication bus fault between door module and BCM
Fault status
Status
U0222 — Lost communication with Door Window Motor A. Module not responding on data bus; affected window control disabled until communication is restored.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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