What is SKS? (Smart Key System)
The SKS stands for Smart Key System. It is an advanced vehicle security and convenience system that allows keyless entry, push-start ignition, and automatic vehicle recognition without inserting a physical key.
Function of the SKS System
- Keyless entry (unlock/lock doors automatically).
- Push start / Stop engine button operation.
- Automatic key recognition when approaching vehicle.
- Anti-theft immobilizer function.
- Remote locking and unlocking.
Components of SKS System
- Smart key fob (transponder key).
- SKS ECU (control module).
- Antenna units inside/outside the vehicle.
- Door handle sensors.
- Start/stop button.
Location of SKS Module
- Usually located under dashboard (driver side).
- Sometimes near fuse box or center console.
- Antenna units placed in doors, trunk, and interior cabin.
Symptoms of a Faulty SKS System
- Car does not detect smart key.
- Push start button not working.
- Doors not locking/unlocking automatically.
- “Key Not Detected” message on dashboard.
- Intermittent key recognition.
OBD / Diagnostic Codes Related to SKS
- B27xx codes – key or antenna communication faults (varies by manufacturer).
- B2799 – Engine immobilizer system fault (common in Toyota systems).
- B2780–B2788 – Antenna or key detection issues.
- U-codes – communication loss with SKS ECU.
SKS Electrical Circuit
The SKS system works through low-voltage digital communication:
- 12V battery supply to SKS ECU.
- Ground circuits.
- CAN Bus communication (CAN High / CAN Low).
- Low-frequency antenna signals (LF signals) for key detection.
- RF communication (radio frequency) between key and ECU.
Voltage Values
- Power supply: 12V system voltage.
- Internal regulated voltage: 5V (control circuits).
- Communication signals: 2.5V–3.5V (CAN bus activity).
- Antenna LF signals: low-frequency AC pulses (varies by system).
Types of Smart Key Systems
- Basic keyless entry system.
- Advanced Smart Key System with push start.
- Full proximity system (automatic unlock/lock when approaching).
Repair / Replacement Cost
- Key reprogramming: medium cost.
- Antenna repair: depends on location and labor.
- Smart key replacement: approximately $50 – $300+.
- SKS ECU replacement: $150 – $800+ depending on vehicle.
Important Notes
SKS issues are often caused by weak key battery, antenna faults, or communication problems rather than ECU failure. Always check key battery and antenna wiring before replacing modules.