Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
4WAS SYSTEM: Fail-safe (4WAS Front Control Unit)
4WAS system enters in the fail-safe mode (4WAS system is stopped), and 4WAS warning lamp turns ON (except DTC "C1633") if an error is detected in 4WAS system component part.
| DTC | Error area and root cause | Contents of fail-safe | ||
|---|---|---|---|---|
| C1621 | 4WAS front motor current valve error is detected. (4WAS front motor current valve is excessively large.) | 4WAS system is stopped. | ||
| C1622 | 4WAS front motor voltage valve or current error valve is detected. (4WAS front motor voltage valve error is detected.) (Voltage valve or current valve error is detected when starting the system.) |
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| C1627 | The indication value from 4WAS front actuator (front wheel angle) differs from the value from 4WAS front control unit. | |||
| C1628 | The front wheel steering angle sensor error is detected. | |||
| C1631 | An error is detected inside 4WAS front control unit. | |||
| C1632 | An error is detected inside 4WAS front control unit. | |||
| C1633 | An error is detected inside 4WAS front control unit. | |||
| C1651 | The ignition voltage signal error is detected. | |||
| C1652 | 4WAS front motor main power supply error is detected. | |||
| C1654 | An error is detected on the main relay power supply inside 4WAS front control unit. | |||
| C1655 | 4WAS front motor 3-phase current error is detected. (Current is not applied to 4WAS front motor) | |||
| C1661 | 4WAS front lock solenoid valve error is detected. (An electric activation error is detected.) | |||
| C1667 | 4WAS front lock solenoid valve (lock) error is detected. (An error is detected in lock condition.) | |||
| C1668 | 4WAS front lock solenoid valve (lock) error is detected. (Excessive force is applied to the lock.) | |||
| C1669 | 4WAS front actuator error is detected. (An error is detected in unlock condition.) | |||
| C1671 | 4WAS front actuator adjustment is not performed. | |||
| C1672 | 4WAS front actuator adjustment is incomplete. | |||
| C1684 | 4WAS communication line(1) data communication error is detected. (An error signal is detected from 4WAS main control unit.) | |||
| C1685 | 4WAS communication line(1) data communication error is detected. (An error signal is detected from 4WAS main control unit.) | |||
| C1686 | An error is detected on 4WAS main control unit side. (4WAS main control unit fail-safe mode) | |||
| U1000 | When 4WAS front control unit is not transmitting or receiving 4WAS communication signal for 2 seconds or more. | |||
| U1002 | When 4WAS front control unit is not transmitting or receiving 4WAS communication signal for 2 seconds or less. | |||
| U1010 | When detecting error during the initial diagnosis of 4WAS controller of 4WAS front control unit | |||
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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