VGRS (Variable Gear Ratio Steering) System General The steering gear ratio will be changed in accordance with the vehicle speed a a -  a +  VGRS system is adopted only for the 3UZ-FE model as standard equipment Basic construction and operation is same as ’05 LX470 Low Ratio (Quick) High Ratio (Slow) Vehicle speed low Vehicle speed high

Rotational Position Sensor (for motor) VGRS System Major Difference from ’05 LX470 Item ’06 GS430 ’05 LX470 Rotational Position Sensor (for motor) Resolver Three Hall ICs System Warning Warning Message VGRS Warning Light Communication CAN, Serial Communication [Major Difference] Resolver is used as rotational position sensor for motor Warning message is displayed on the multi information display (VGRS warning light is discontinued) CAN communication is used

VGRS System System Diagram VGRS ECU Steering Angle Sensor VGRS Actuator VGRS ECU Serial Communication Lock Mechanism Spiral Cable Motor Skid Control ECU CAN Resolver Temp. Sensor Engine ECU (ECM) CAN communication is used CAN DLC3 BEAN Gateway ECU Serial Communication EPS ECU Combination Meter

VGRS system not operates Steering Gear Ratio Confidential Slow 19 VGRS system not operates 17 Steering Gear Ratio 15 Lock to Lock : 3.2 At very low speed: Quick gear ratio to reduce the driver's steering angle At low or middle speed: Optimum steering gear ratio to vehicle responds with more agility and handles more easily At high speed: Slow gear ratio to ensures a stable vehicle response Quick 100 (62) 200 (124) Km/h (mile) Lock to Lock : 2.7 Vehicle Speed

VGRS System System Operation VGRS ECU VGRS Actuator Motor Gear Map Steering Angle Sensor VGRS Actuator Motor Rack & Pinion Gear Control Signal (Target Operating Angle) VGRS ECU Steering Angle Map Calculate actuator target operating angle Actuator Operating Angle Skid Control ECU Vehicle Speed Vehicle Speed

VGRS System System Operation VGRS ECU adds the supplemental assist with steering speed to reduce delay of vehicle response Normal Operation Actuator Output In order to operate this control, serial communication with steering angle sensor is used (Serial communication speed is faster than the CAN communication) Assist

VGRS Actuator Assembly VGRS System VGRS Actuator VGRS Actuator Spiral Cable Steering Wheel Lock Mechanism Motor Do not overhaul the VGRS actuator Rack & Pinion VGRS Actuator Assembly Reduction Mechanism

VGRS System VGRS ECU Spiral Cable Flexible flat cable is used Spiral Cable (Flexile Flat Cable) VGRS ECU Control Signal, Power Source Rotational angle and rotational direction of the motor Motor

Service Point (VGRS System) Spiral Cable Before installing VGRS actuator, secure the neutral position of this cable 2 turns Lock After 2 turns Neutral Position Mark Same as spiral cable for driver’s airbag 1. Turn the cable clockwise until it becomes harder to turn 2. Then turn the cable counterclockwise about 2 turns Slit

Lock Holder (Motor Shaft) VGRS System Lock Mechanism Locks the motor shaft Lock Mechanism A – A Cross Section Lock Holder (Motor Shaft) Solenoid A A Lock mechanism locks the motor shaft Motor Shaft Return Spring Lock Lever (Housing)

VGRS System Lock Mechanism Lock / unlock operation Solenoid “ON” Solenoid “OFF” Solenoid ON (Unlock): System is normal Solenoid OFF (Locked by return spring force): Engine is stopped or system fail Unlock Lock

Rotation Angle Sensor (Resolver) VGRS System Motor A compact high-output low-noise brush-less motor Rotation Angle Sensor (Resolver) Brush-less Motor Motor Shaft Magnet Coil Rotation angle sensor (resolver) outputs 2 signals with which the phase lagged 90 degrees Motor rotation angle can be detected by comparing the 2 signal waveforms Reduction Mechanism

VGRS System Reduction Mechanism The strain wave gearing type reduction mechanism Motor Stator Gear Stator Gear Flexible Gear Wave Generator Flexible Gear Driven Gear Strain wave gearing type reduction mechanism is compact and high precision, few components, and higher reduction ratio Wave Generator Driven Gear Output Shaft

Wave Generator (input) VGRS System Reduction Mechanism Components Stator Gear (input) Driven Gear (output) Wave Generator (input) Flexible Gear Stator Gear (Input): Coupled to the housing of the VGRS actuator Flexible Gear:Flexible metal body Gear teeth are meshed with the inside of both stator gear and driven gear Driven Gear (Output): Coupled to the output shaft of the VGRS actuator Wave Generator (Input): Consists an oval-shaped cam and bearing, and rotated by the motor Steering Wheel Rack & Pinion

The difference of number of teeth VGRS System Reduction Mechanism Number of teeth Stator Gear (input) Driven Gear (output) Wave Generator (input) Flexible Gear The difference of the number of teeth is used for the reduction mechanism 100 100 102 The difference of number of teeth

VGRS System Reduction Mechanism Construction Meshing Not meshing Stator Gear Flexible Gear Wave Generator Meshing Ball Bearing is between flexible gear and wave generator Flexible gear is oval shaped by wave generator Not meshing View from stator gear side (Steering wheel side)

VGRS System Reduction Mechanism Operation of strain wave gearing Motor Shaft Flexible Gear (100 teeth) Wave Generator Stator Gear (102 teeth) Ball Bearing (Between flexible gear and wave generator) View from stator gear side (Steering wheel side)

View from stator gear side VGRS System Reduction Mechanism Operation of strain wave gearing [Operation of strain wave gearing] 1. Flexible gear is flexed into an oval shape by wave generator 2. Flexible gear teeth meshes with stator gear teeth and driven gear 3. During wave generator rotation, the meshed area of the flexible gear and stator gear / driven gear moves in sequence 4. After the wave generator makes one turn, the flexible gear is shifted by 2 teeth because the flexible gear has 2 fewer teeth than the stator gear 5. The driven gear and flexible gear have the same number of teeth, so their rotational movements are identical 6. The flexible gear is shifted by 2 teeth = The driven gear shifted by 2 teeth (= Actuator output) Stator gear fixed View from stator gear side (Steering wheel side)

VGRS System Reduction Mechanism Operation of strain wave gearing Stator Gear (102 teeth) Flexible Gear (100 teeth) Shifts by 2 teeth Wave generator makes one turn Every time motor rotates, stator gear and flexible gear (driven gear) shifts by two teeth This shift is used as actuator output Click! Movie Driven Gear (100 teeth)

VGRS System Reduction Mechanism Reduction gear ratio Gear Ratio 50 : 1 Flexible gear rotates one turn Wave generator (motor) rotates 50 turns Reduction Gear Ratio: 50 Gear Ratio 50 : 1 Motor Flexible Gear

M VGRS System Operation Vehicle speed is low (quick ratio) Add steering angle M [Vehicle speed is low (quick ratio)] When the steering wheel is turned to the left, motor rotates the clockwise and adds steering angle Click! Movie

M VGRS System Operation Vehicle speed is mid. (normal ratio) No assist [Vehicle speed is middle (normal ratio)] When the steering wheel is turned to the left, motor does not operates and no assist Click! Movie No assist

Reduces steering angle VGRS System Operation Vehicle speed is high (slow ratio) M [Vehicle speed is high (slow ratio)] When the steering wheel is turned to the left, motor rotates the counterclockwise and reduces steering angle Click! Movie Reduces steering angle

VGRS System Warning Message VGRS warning message for the system malfunction Master warning light is light up when the VGRS warning message is displayed Warning Message

VGRS System Diagnosis 29 DTCs for VGRS system DTC Detection Item C1591 VGRS Actuator Neutral Position Calibration Undone C1592 VGRS Actuator Neutral Position Calibration Incomplete C1593 VGRS Actuator Standard Position Malfunction C1595 Lost Communication with Steering Angle Sensor Module C1597 Lost Communication between VGRS and EPS C15A1 VGRS Actuator Malfunction C15A2 C15A3 C15A4 C15A5 C15A6 C15A9 Lock Holder Deviation Detection C15AA Lock Mechanism Release Incomplete C15AB Lock Mechanism Insertion Malfunction

VGRS System Diagnosis 29 DTCs for VGRS system DTC Detection Item C15B1 VGRS ECU Malfunction C15B2 C15B3 C15B4 C15C1 Steering Angle Sensor Malfunction C15C2 Steering Angle Sensor B+ Malfunction C15C3 Brake System Control Module Malfunction C15C6 IG Power Supply Voltage Malfunction C15C7 DC Motor Power Source Voltage Malfunction C15C8 Power Supply Relay Failure U0100 Lost Communication With ECM/PCM "A" U0122 Lost Communication With Vehicle Dynamics Control Module U0123 Lost Communication With Yaw Rate Sensor Module U0126 Lost Communication With Steering Angle Sensor Module U0131 Lost Communication With Power Steering Control Module

Initialization and Calibration VGRS System Initialization and Calibration Item Steering Angle Sensor Initialization Calibration Replacement VGRS ECU VGRS Actuator  Repairing steering system parts Reconnect the battery terminal  Reconnect the connectors Steering Angle Sensor Skid Control ECU [Steering Angle Sensor Initialization] - Restore the neutral position of steering wheel - Center the steering wheel position [Calibration] - Initialize and calibrate the VGRS actuator angle - Center the steering wheel position (when steering wheel is still off-center after completing the steering angle sensor initialization)

Service Point (VGRS System) Initialization and Calibration Steering angle sensor initialization Drive the vehicle on a straight road at 35 km/h (22 mph) or more for 5 sec. or longer Neutral position of steering wheel is restored Steering wheel is automatically centered Perform normal cornering 2 to 3 times [Steering Angle Sensor Initialization] If steering angle sensor initialization is not completed, VGRS system is stopped 1. Drive the vehicle on a straight road at 35 km/h (22 mph) or more for 5 sec. or longer Note: Steering wheel will still off-center Neutral position of steering wheel is restored in this step 2. After performing normal cornering 2 to 3 times, the steering wheel position is automatically corrected 3. Confirm the steering angle sensor initialization is completed Access the VGRS data list using the Intelligent Tester II (Hand-held Tester) and confirm the “Straight Angle Valid Flag” parameter reads VALID Note: If INVALID, return to first step (If INVALID returns again, check for DTCs and perform VGRS system calibration) Using IT II, Confirm the steering angle sensor initialization is completed

Service Point (VGRS System) Initialization and Calibration Calibration Face the tire straight ahead IG/ON Engine OFF Using IT II, perform calibration in accordance with the “Steering Angle Adjust” Confirm the steering wheel from lock to lock is 2.7-turn [Calibration] 1. Face the tire straight ahead, IG/ON, Engine OFF 2. Using Intelligent Tester II (Hand-held Tester), perform calibration in accordance with the “Steering Angle Adjust” from the VGRS DIAGNOSTIC MENU 3. Turn the steering wheel from lock to lock to check that it rotates approx. 2.7 turns 4. Perform the actuator sensor learning confirmation procedure to confirm the system calibration has been completed properly 5. Drive vehicle to confirm steering wheel is centered Perform the actuator sensor learning confirmation Click for Detail Drive vehicle to confirm steering wheel is centered

Service Point (VGRS System) Initialization and Calibration Actuator sensor learning confirmation (detail) Start the engine Continue the turning for 3 sec. Turn the steering wheel to the left 90 and then back to center Repeat 15 times While turning, stop the engine Turn the steering wheel to the right 90 and then back to center Hold the steering wheel for 3 sec. Turn the steering wheel slowly to the left [Actuator sensor learning confirmation] 1. Start the engine 2. Turn the steering wheel from center to the left 90° and then back to center 3. Turn the steering wheel from center to the right 90° and then back to center 4. Hold the steering wheel in the centered position for 3 sec. 5. Perform the following check procedure a. Turn the steering wheel slowly to the left b. While turning the steering to the left, turn off the engine c. Continue to turn the steering wheel slowly to the left 3 sec. 6. Repeat step1 to 5 for 15 times Note: DTC C15A9 requires that the fault occurs 5 consecutive times to set The confirmation procedure must be performed multiple times to ensure the condition does not repeat 7. Check that the DTC is not output Note: If C15A9 is set, repeat the calibration for a second time (If C15A9 is set again, replace the VGRS actuator) Check that the DTC is not output

Reference (VGRS System) Components Wave Generator Flexible Gear Motor M Output (Rack & Pinion) Steering Wheel Actuator Housing Driven Gear Stator Gear