Fail Safe

EPS system

EPS system enters the fail-safe mode (that allows the steering force to be controlled without impairing the drive ability) if any of the input/output values to/from EPS system (power steering control unit) deviate from the standard range.
NOTE: The system enters the fail-safe mode if the engine speed remains at 1,500 RPM or more for over 10 seconds while the vehicle is stopped. This is normal.
The fail-safe function is canceled when a vehicle speed signal of 2 km/h (1.2 MPH) or more is inputted or the key switch is turned OFF→ON. EPS system restores the normal operation at that time.

Fig 1: Power Steering Solenoid Valve Voltage Graph
Courtesy of NISSAN MOTOR CO., U.S.A.

STEERING SOLENOID VALVE REFERENCE CHART

Function	Warning lamp	DTC No.	Detection point (malfunction part)	Malfunction part and cause
Fail-safe function	-	-	Vehicle speed signal input	Engine speed is 1,500 RPM or more and there is no vehicle speed signal input for over 10 seconds during vehicle travel. Vehicle speed signal has abruptly dropped from 30 km/h (19 MPH) or more to 2 km/h (1.2 MPH) or less within 1.4 seconds.