Here’s a brief description and comparison of the power sliding door motor systems used in the Toyota Vellfire 20, Estima, and Alphard (mainly second-generation models, around 2008–2014):

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1. Toyota Vellfire 20 Series (2008–2014)

• Sliding Door Type: Electrically operated (power sliding door), usually on both sides for higher trims.
• Motor Location: Installed inside the sliding door or within the door panel track system.
• Operation: Motor-driven cable mechanism with sensors for soft close and obstacle detection.
• Common Parts:
  
• Sliding door motor assembly
• Cable reel (for drive wire)
• Control unit (integrated with body ECU)
• 
  
• Symptoms of Failure:
  
• Door doesn’t open/close automatically
• Grinding noise from motor area
• Incomplete closing or auto-reversal
• 
  

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2. Toyota Estima (Aeras / Hybrid – 2nd & 3rd gen, 2006–2019)

• Sliding Door Type: Power sliding doors available on most variants.
• Motor System: Similar cable-pulley system using a motorized unit, often mounted near the rear wheel well or inside the sliding rail.
• Control Integration: Controlled via main body ECU; also operated via dashboard switch, key fob, or interior door handles.
• Key Features:
  
• Anti-pinch sensor
• Soft close
• Easy access function
• 
  

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3. Toyota Alphard 20 Series (2008–2014)

• Sliding Door System: High-end with dual power doors and high sensitivity anti-pinch systems.
• Power Door Motor Unit:
  
• Uses a motor and steel cable to move the door along the rail
• Gear reduction assembly to control speed and force
• 
  
• Control System: More advanced, connected to smart key system, dashboard switches, and sliding door handles.
• Motor Assembly Components:
  
• Door ECU
• Position sensor
• Pulley cable drive
• Limit switches or hall sensors for door position
• 
  

⚠️ Common Issues Across All Models:

• Cable Fraying or Breaking: One of the most common failure points.
• Motor Burnout: Can happen due to high use or obstruction.
• Sensor Malfunction: Especially anti-pinch or soft-close sensors.
• ECU Sync Problems: Sometimes needs recalibration or reset.

🛠️ Tips:

• Diagnosis: Use a scan tool to check for fault codes in the body control module.
• Maintenance: Keep the rails clean and lubricated; avoid obstructing the door during motion.
• Replacement: Motors and cable assemblies can often be replaced as a unit. Aftermarket options exist, but OEM is more reliable.

Would you like an exploded diagram or part number references for any of these vehicles?