Electronically Controlled Power Steering System Function
- Vehicle speed sensing electronically controlled power steering (that properly controls the steering force by the vehicle speed) has been adopted. When it is normal, it controls the power steering solenoid valve according to the vehicle speed as shown in the figure and makes the steering force proper.
- For the models with RAS (Rear Active Steer), RAS control unit performs the same control as power steering control unit. For schematic, refer to " «SCHEMATIC»(ref-239134-S21317512322006072700000) " and trouble diagnosis, refer to " «DIAGNOSIS CHART BY SYMPTOM 2»(ref-239134-S42711659622006072700000) ".
Scheme 55
Fail-Safe Function
When the fail-safe function operate, it controls power steering solenoid valve by the engine speed as shown in the figure and maintains the steering force.
Scheme 56
FAIL-SAFE INPUT/CANCEL CONDITIONS
| Input conditions | Cancel conditions |
|---|---|
| When vehicle runs at an engine speed of 1,500 rpm or higher and no vehicle speed signal is received for 10 seconds. | A vehicle speed of 2 km/h (1.2 MPH) or more is input. Turn the ignition switch ON after turning it OFF. |
| The continuous vehicle speed signal 30 km/h (19 MPH) or more suddenly drops to less than 2 km/h (1.2 MPH) within 1.4 seconds. |
FAIL-SAFE CHART
| CAUTION | Fail-safe function is activated when the engine runs at 1,500 rpm or higher for 10 seconds with the vehicle stopped. This is normal and the fail-safe function is automatically deactivated when a vehicle speed signal of 2 km/h (1.2 MPH) or higher is input or the ignition switch is turned OFF. |
Scheme 57
Scheme 58
- The most important point to perform trouble diagnosis is to understand systems (control and mechanism) in vehicle thoroughly.
- It is also important to clarify customer complaints before inspection. First of all, reproduce symptom, and understand it fully. Ask customer about his/her complaints carefully. In some cases, they will be necessary to check symptom by driving vehicle with customer. CAUTION: Customers are not professionals. Do not assume "maybe customer means..." or "maybe customer mentioned this symptom".
- It is essential to check symptoms right from beginning in order to repair a malfunction completely. For an intermittent malfunction, it is important to reproduce symptom based on interview with customer and past examples. Do not perform inspection on ad hoc basis. Most intermittent malfunctions are caused by poor contacts. In this case, it will be effective to shake suspected harness or connector by hand. When repairs are performed without any symptom check, no one can judge if malfunction has actually been eliminated.
- Always read "GI General Information" to confirm general precautions. Refer to " «GENERAL PRECAUTIONS»(ref-239095-S33781148372006072700000) ".
Scheme 59
STANDARD BY CIRCUIT TESTER AND OSCILLOSCOPE
| CAUTION | When checked using a circuit tester for voltage measurement, connector terminals should not be forcefully extended. |
CONTROL UNIT INPUT/OUTPUT SIGNAL STANDARD Terminal Measuring point Measuring condition Standard + (wire color) - 1 (GR) Ground IGN Ignition switch ON. Battery voltage (Approx. 12 V) 2 (B) Ground - - 3 (L) Vehicle speed signal (2-pulse) At 40 km/h (25MPH) 5 (Y) Engine speed signal At idle after warming up At approx. 2,000 rpm 7 (G) Power steering solenoid valve Normal (Vehicle speed) 0 km/h (0 MPH) Approx. 4.4 - 6.6 V 100 km/h (62 MPH) Approx. 2.4 - 3.6 V In fail-safe mode (Engine speed) 0 - 1,500 rpm Approx. 4.4 - 6.6 V 1,500 - 3,000 rpm Approx. 3.5 V More than 3,000 rpm Approx. 2.1 V
Scheme 60
Scheme 61
Scheme 62
POWER SUPPLY CIRCUIT TERMINAL LOOSENESS AND BATTERY
Check battery terminals for looseness on both positive and negative ones and ground connection. Also make sure that battery voltage does not drop.
Scheme 63
Scheme 64
- CHECK POWER STEERING CONTROL UNIT CONNECTOR Turn ignition switch OFF, disconnect power steering control unit harness connector, and check terminal for deformation, disconnection, looseness, etc. OK or NG OK: GO TO 2. NG: Connector terminal connection is loose, damaged, open, or shorted. Repair or replace the terminal.
- CHECK POWER STEERING CONTROL UNIT GROUND CIRCUIT Disconnect power steering control unit harness connector M8, and then check continuity between power steering control unit harness connector M8 and ground. Terminal 2 - Ground: Continuity exist. OK or NG OK: GO TO 3. NG: Ground circuit open or shorted. Repair or replace any inoperative parts.
- CHECK POWER STEERING CONTROL UNIT POWER SUPPLY CIRCUIT Turn ignition switch ON, and then check voltage between power steering control unit harness connector M8 and ground. Terminal 1 - ground: Battery voltage (Approx. 12 V) OK or NG OK: Power supply and ground circuit are normal. NG: Power supply circuit open or shorted. Repair or replace any inoperative parts.
RAS (Rear Active Steer) Function
| Part name | Function |
|---|---|
| RAS control unit | Calculate the vehicle speed signal from CAN communication and the signals from steering angle sensor and rear wheel steering angle sensor by a computer, and then control the rear wheel steering angle. Fail-safe function is activated when the electrical system is malfunctioning. The output signal to the actuator is turned OFF during this mode. At that time, the RAS warning lamp illuminates and indicates the system is malfunctioning. It performs the communication control function with other control units via CAN communication. This enables system diagnosis with CONSULT-II. |
| RAS actuator | The efficiency of the rear wheel steer improves by locating the electric motor actuator into the lower link of rear suspension. |
| Steering angle sensor | Measure the steering angle and send it to RAS control unit via CAN communication. It is shared with the steering angle sensor for VDC. |
| Rear wheel steering angle sensor | It sends the rear wheel steering angle status to RAS control unit. The accuracy of rear wheel steer improves by comparing the vehicle speed signal from CAN communication with the rear wheel steering angle target value calculated from the wheel angle sensor signal, and it controls them. There are 2 types of rear wheel steering angle sensors (main/sub). If one of them is malfunctioning, the other operates the fail-safe mode and stops the control. |
| RAS warning lamp | It turns on when the fail-safe function is operated and indicates that a RAS control malfunction has occurred. It turns on when ignition switch turns on and turns off after the engine is started. It indicates the suspect system by blinking when performing the self-diagnosis (without CONSULT-II). |
RAS (REAR ACTIVE STEER) FUNCTION
In the event there is a malfunction with the electrical system, the RAS control is stopped and the fail-safe mode is activated. At that time, it indicates the malfunction by turning the RAS warning lamp ON and stops the rear wheel control.
Scheme 65
- The most important point to perform trouble diagnosis is to understand systems (control and mechanism) in vehicle thoroughly.
- It is also important to clarify customer complaints before inspection. First of all, reproduce symptom, and understand it fully. Ask customer about his/her complaints carefully. In some cases, they will be necessary to check symptom by driving vehicle with customer. CAUTION: Customers are not professionals. Do not assume "maybe customer means..." or "maybe customer mentioned this symptom".
- It is essential to check symptoms right from beginning in order to repair a malfunction completely. For an intermittent malfunction, it is important to reproduce symptom based on interview with customer and past examples. Do not perform inspection on ad hoc basis. Most intermittent malfunctions are caused by poor contacts. In this case, it will be effective to shake suspected harness or connector by hand. When repairs are performed without any symptom check, no one can judge if malfunction has actually been eliminated.
- After diagnosis, make sure to perform "ERASE MEMORY". Refer to " «HOW TO ERASE SELF-DIAGNOSTIC RESULTS»(ref-239134-S20220698432006072700000) ".
- Always read "GI General Information" to confirm general precautions. Refer to " «HOW TO USE THIS INFORMATION»(ref-239095-S37075491802006072700000) ".
Scheme 66
Scheme 67
Scheme 68
CIRCUIT TESTER REFERENCE VALUE
| CAUTION | When checked using a circuit tester for voltage measurement, connector terminals should not be forcefully extended. |
| Terminal | Measuring point | Measuring condition | Standard | ||
|---|---|---|---|---|---|
| + (wire color) | |||||
| 1 (L) | CAN-H | ||||
| 4 (G) | Ground | RR MAIN SIG | Neutral | Approx. 2.4 V | |
| 5 (W) | RR VCC | Ignition switch ON | Approx. 5 V | ||
| Ignition switch OFF | Approx. 0 V | ||||
| 7 (R) | RR SUB SIG | Neutral | Approx. 2.4 V | ||
| 8 (P) | CAN-L | ||||
| 15 (B/W) | Ground | RR SEN GND | Continuity exit | ||
| 22(P/L) | STOP/L SW | Brake pedal depressed | Battery voltage (Approx. 12 V) | ||
| Brake pedal not depressed | Approx. 0 V | ||||
| 25 (L/W) | RLY | Ignition switch ON | Battery voltage (Approx. 12 V) | ||
| Ignition switch OFF | Approx. 0 V | ||||
| 26 (G/W) | WARN | ON | Approx. 1.4 V or less | ||
| OFF | Ignition voltage: 2.8 V or more | ||||
| 27 (G/B) | IGN | Ignition switch ON | Battery voltage (Approx. 12 V) | ||
| Ignition switch OFF | Approx. 0 V | ||||
| 34 (B) | GND | Continuity exit | |||
| 36 (LG) | P/S SOL | Normal (Vehicle speed) | 0 km/h (0 MPH) | Approx. 4.4 - 6.6 V | |
| 100 km/h (62 MPH) | Approx. 2.4 - 3.6 V | ||||
| In fail-safe mode (Engine speed) | 0 - 1,500 rpm | Approx. 4.4 - 6.6 V | |||
| 1,500 - 3,000 rpm | Approx. 3.5 V | ||||
| 3,000 rpm or more | Approx. 2.1 V | ||||
| 37 (L/Y) | MOTOR VCC | Ignition switch ON | Battery voltage (Approx. 12 V) | ||
| Ignition switch OFF | Approx. 0 V | ||||
| 38 (W) | MTR-1 (RH) | ||||
| 39 (B) | MTR-2 (LH) | ||||
| 40 (B/W) | MOTOR GND | Continuity exit | |||
CIRCUIT TESTER REFERENCE VALUE
STANDARD BY CONSULT-II
| CAUTION | The output signal indicates the RAS control unit calculation data. The normal values will be displayed even in the event that the output circuit (harness) is open. |
| Monitor item | DATA MONITOR | Malfunction inspection checklist | |
|---|---|---|---|
| Condition | Reference values | ||
| VHCL SPEED SE (km/h) | Ignition switch ON or engine running | Almost in accordance with the speedometer display. It is not a malfunction, through it might not be corresponding just after ignition switch is turned ON. | " INSPECTION 4: VEHICLE SPEED SIGNAL " |
| STEERING ANG (°) | Turning steering wheel clockwise or counterclockwise. | Displays the angle when the steering wheel turns from the neutral position | " INSPECTION 5: STEERING ANGLE SIGNAL MALFUNCTION " |
| ENGINE SPEED (rpm) | Engine running | Almost in accordance with tachometer display | " INSPECTION 8: ENGINE SPEED SIGNAL MALFUNCTION " |
| POWER STR SOL (A) | Accelerate the vehicle from 0 to 100 km/h (0 to 62 MPH) | 0 km/h (0 MPH): Approx. 1.10 A 100 km/h (62 MPH): Approx. 0.54 A | " DIAGNOSIS CHART BY SYMPTOM 2 " |
| RR ST ANG-MAI (V) | Perform the ACTIVE TEST and stroke the actuator (with tires off the ground) | Neutral: Approx. 2.4 V Turn steering wheel to right for full stroke: Approx. 4.4 V Turn steering wheel to left for full stroke: Approx. 0.4 V | " INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION " |
| RR ST ANG- SUB (V) | |||
| RR ST ANG-VOL (V) | Ignition switch ON or engine running | Approx. 5 V | " INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION " |
| C/U VOLTAGE (V) | Battery voltage (Approx. 12 V) | " INSPECTION 1: RAS CONTROL UNIT MALFUNCTION " | |
| MOTOR VOLTAGE (V) | Battery voltage (Approx. 12V) | " INSPECTION 2: MOTOR POWER SUPPLY SYSTEM " | |
| MOTOR CURRENT (A) | Perform the ACTIVE TEST and stroke the actuator. | It is normal when there is the current output at stroke | " INSPECTION 2: MOTOR POWER SUPPLY SYSTEM " |
| MTR CRNT OPE (A) | Turning steering wheel clockwise or counterclockwise while ignition switch is ON or running the engine | Neutral (Steering force is zero and straight-ahead position): Approx. 0 A The value is changed according to steering left or right | " INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION " |
| STOP LAMP SW | Depressing or releasing brake pedal | Brake pedal depressed: ON | " INSPECTION 10: STOP LAMP SWITCH HARNESS " |
| Brake pedal not depressed: OFF | |||
| RAS RELAY | Ignition switch ON or engine running | Ignition switch ON: ON | " INSPECTION 2: MOTOR POWER SUPPLY SYSTEM " |
| FAIL SAFE | Not activated | Self-diagnosis and suspect system inspection on DATA MONITOR | |
| WARNING LAMP (ON/OFF) | RAS warning lamp ON: ON RAS warning lamp OFF: OFF | Warning lamp circuit inspection | |
CONSULT-II CALCULATION DATA
FUNCTION
CONSULT-II can display each self-diagnostic item using the diagnostic test modes shown following.
| Mode | Function | Reference |
|---|---|---|
| SELF-DIAG RESULTS | Receives self-diagnosis results from RAS control unit and indicates DTCs. | " SELF-DIAG RESULT MODE " |
| DATA MONITOR | Receives input/output signals from RAS control unit and indicates and stores them to facilitate locating cause of malfunctions. | " DATA MONITOR MODE " |
| CAN DIAG SUPPORT MNTR | Monitors transmitting/receiving status of CAN communication. | " CAN COMMUNICATION " |
| ACTIVE TEST | Sends command to RAS actuator to change output signals and check operation of output system. | " ACTIVE TEST MODE " |
| ECU PART NUMBER | Displays RAS control unit part number. | " RAS CONTROL UNIT PART NUMBER " |
CONSULT-II FUNCTION (RAS)
CONSULT-II SETTING PROCEDURE
Refer to " CONSULT-II START PROCEDURE ".
Display Item List
| CAUTION | When malfunctions are detected in several systems, including the "CAN COMM [U1000]" and "CONTROL_UNIT (CAN) [U1010]", inspect the CAN communication system. |
| VDC | Diagnostic item | Diagnostic item is detected when... | Check items |
|---|---|---|---|
| C1923 | STEERING_ANGLE_SEN [NO_CHANGE] (. a) | While driving at 60 km/h (37 MPH) or more, steering angle does not change for a while. | INSPECTION 5: STEERING ANGLE SIGNAL MALFUNCTION |
| C1924 | STEERING_ANGLE_SEN [NO_NEUT_STATE] (. b) | When driving some distance, no neutral signal (ON signal) is input. | INSPECTION 5: STEERING ANGLE SIGNAL MALFUNCTION |
| C1915 | RR_ST_ANGLE_SENSOR [MAIN_SIGNAL] (. a) | The main sensor input signal is malfunctioning for some time against the sensor power supply value. | INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION |
| C1916 | RR_ST_ANGLE_SENSOR [SUB_SIGNAL] (. b) | When the main sensor input signal is 2.4 - 2.6 V, the sub sensor input signal is malfunctioning for some time compared to the sensor power supply value. | INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION |
| C1917, C1918 | RR_ST_ANGLE_SENSOR [OFFSET_SIG1,2] (. c) | An excessive difference has occurred in the input values of main sensor and sub sensor. | INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION |
| C1914 | RR_ST_ANGLE_SENSOR [ABNORMAL_VOL] (. d) | Higher or lower value compared to the standard voltage. | INSPECTION 6: REAR MAIN SIGNAL AND REAR SUB SIGNAL MALFUNCTION |
| C1921 | MOTOR_OUTPUT | No engine speed is input for a certain time. | INSPECTION 8: ENGINE SPEED SIGNAL MALFUNCTION |
| C1911 | MOTOR_VOLTAGE [LOW_VOLTAGE] (. a) | The motor power supply voltage is lower than ignition power supply voltage with RAS motor relay ON. | INSPECTION 2: MOTOR POWER SUPPLY SYSTEM |
| C1912 | MOTOR_VOLTAGE [BAD_OBSTRCT] (. b) | The motor power supply voltage is inputting for some time with motor power supply OFF by RAS control unit. | INSPECTION 2: MOTOR POWER SUPPLY SYSTEM |
| C1913 | MOTOR_OUTPUT [ABNORMAL_SIG] (. a) | When the motor current value is 10A or more, actual output is excessively low and the condition continues for some time. | INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION |
| C1902 | MOTOR_OUTPUT [REV_CURRENT] (. c) | The current flows in the opposite direction when the motor current is output. | INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION |
| C1903 | MOTOR_OUTPUT [NO_CURRENT] (. d) | The current flows when the motor current is not output. | INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION |
| C1904 | MOTOR_OUTPUT [OVERCURRENT] (. e) | The excessive high current flows when the motor current is output. | INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION |
| C1910 | MOTOR_OUTPUT [MOTOR_LOCK] (. b) | When 17 A or more current flows to the motor, the rear wheel steering angle sensor signal does not change for some time. | INSPECTION 3: RAS MOTOR OUTPUT MALFUNCTION |
| C1919 | VEHICLE_SPEED_SEN [NO_SIGNAL] | No vehicle speed signal is input for some time. | INSPECTION 4: VEHICLE SPEED SIGNAL |
| C1900 | CONTROL_UNIT [ABNORMAL1 - 9] | Control unit malfunction | INSPECTION 1: RAS CONTROL UNIT MALFUNCTION |
| C1901 | |||
| C1905 | |||
| C1906 | |||
| C1907 | |||
| C1908 | |||
| C1909 | |||
| C1922 | |||
| C1928 | |||
| C1920 | STEERING_ANGLE_SEN [NO_SIGNAL] | No steering angle signal is input for some time. | INSPECTION 5: STEERING ANGLE SIGNAL MALFUNCTION |
| C1926 | STEERING_ANGLE_SEN | An unexpected signal is input. Steering angle sensor outputs the malfunction signal. | INSPECTION 5: STEERING ANGLE SIGNAL MALFUNCTION |
| C1929 | VDC | ABS actuator and electric unit (control unit) outputs the malfunction signal. | VDC |
| U1000 | CAN COMM CIRCUIT | When a control unit (except for RAS) is not transmitting or receiving CAN communication signal 2 seconds or less. | INSPECTION 9: CAN COMMUNICATION SYSTEM MALFUNCTION |
| U1010 | CONTROL_UNIT [CAN] | When detected error during the initial diagnosis of CAN controller of each control unit. | INSPECTION 9: CAN COMMUNICATION SYSTEM MALFUNCTION |
DISPLAY ITEM LIST
| Item (Display or Unit) | Remarks |
|---|---|
| VHCL SPEED SE (km/h) | Vehicle speed received via CAN communication is displayed. |
| STEERING ANG (°) | Steering angle received via CAN communication is displayed. |
| ENGINE SPEED (rpm) | Engine speed received via CAN communication is displayed. |
| POWER STR SOL (A) | Power steering solenoid controlling current that RAS control unit outputs is displayed. |
| RR ST ANG_MAI (V) | Rear wheel steering angle main sensor output voltage is displayed. |
| RR ST ANG_SUB (V) | Rear wheel angle sub sensor output voltage is displayed. |
| RR ST ANG_ VOL (V) | Voltage supplied from RAS control unit to rear wheel steering angle sensor is displayed. |
| C/U VOLTAGE (V) | Voltage supplied to RAS control unit is displayed. |
| MOTOR VOLTAGE (V) | Voltage supplied from RAS control unit to RAS motor is displayed. |
| MOTOR CURRENT (A) | RAS motor relay controlling current that RAS control unit outputs is displayed. |
| MOTOR CRNT OPE (A) | Current commanded value to RAS motor is displayed. |
| RR ANG OPE (°) | Angle commanded value to rear wheel steering angle sensor is displayed. |
| STOP LAMP SW (ON/OFF) | Condition of stop lamp switch ON/OFF is displayed. |
| HICAS RELAY (ON/OFF) | RAS motor relay ON/OFF condition is displayed. |
| FAILSAFE (ON/OFF) | Fail-safe ON/OFF condition is displayed. |
| WARNING LAMP (ON/OFF) | RAS warning lamp operating condition is displayed. |
DISPLAY ITEM LIST
RAS CONTROL UNIT PART NUMBER
- Perform "CONSULT-II Start Procedure". Refer to " «CONSULT-II START PROCEDURE»(ref-239095-S42554850072006072700000) ".
- The part number described on RAS control unit sticker is displayed.
REAR WHEEL STEERING ANGLE SENSOR
- Disconnect rear wheel steering angle sensor harness connector B104.
- Check resistance of rear wheel steering angle sensor side connectors.
| Terminal 2 - 3 | Approx. 1 kohm |
|---|---|
| Terminal 4 - 3 | |
| Terminal 1 - 3 | Approx. 1.25 kohm |
RESISTANCE CHECK
