Power Steering: Overview Toyota Prius II рестайлинг

SYSTEM DESCRIPTION

1. DESCRIPTION The electronic power steering system generates torque through the operation of the motor and the reduction gear installed on the column shaft in order to assist steering effort. Directions and amount of assisting power are determined by signals from the torque sensor built into the steering column assembly and by the power steering ECU, and controlled in accordance with vehicle speed. As a result, steering effort is controlled to be light during low speed driving and moderately high during high speed driving. Power steering ECU: The power steering ECU calculates assisting power based on a steering torque signal from the torque sensor and a vehicle speed signal from the skid control ECU. It generates specified assisting torque by controlling current to the motor. Torque sensor: The torque sensor detects steering effort generated when the steering wheel is turned and converts it to an electrical signal. Power steering motor: The power steering motor is activated by the current from the power steering ECU and generates torque to assist steering effort.

DESCRIPTION

The torque sensor converts rotation torque input to the steering wheel into an electrical signal and sends it to the ECU. Based on this signal, the ECU detects steering effort.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. READ VALUE OF TECHSTREAM (TORQUE SENSOR) Connect the Techstream (with CAN VIM) to the DLC3. Turn the power switch ON (IG). Turn the Techstream on. Check the torque sensor output value. Enter the following menus: Chassis / EMPS / Data List. EMPS DATA LIST Tester Display Item Description / Range Diagnostic Note Normal Condition Torque Sensor 1 Output Torque sensor 1 output value / min.: 0 V, max.: 5 V Steering wheel is not turned (without load) 2.3 to 2.7 V Turning steering wheel to right with vehicle stopped 2.5 to 4.7 V Turning steering wheel to left with vehicle stopped 0.3 to 2.5 V Torque Sensor 2 Output Torque sensor 2 output value / min.: 0 V, max.: 5 V Steering wheel is not turned (without load) 2.3 to 2.7 V Turning steering wheel to right with vehicle stopped 2.5 to 4.7 V Turning steering wheel to left with vehicle stopped 0.3 to 2.5 V Read the values of "Torque Sensor 1 Output" and "Torque Sensor 2 Output" on the Techstream display when the steering wheel is centered (without load). Standard voltage: 2.3 to 2.7 V Check the difference in the values of "Torque Sensor 1 Output" and "Torque Sensor 2 Output" when the steering wheel is centered (without load). Standard voltage: 0.3 V or less Read the value of the torque sensor on the tester display when the steering wheel is turned. Turn the steering wheel from its center position to the right full lock position and read the values of "Torque Sensor 1 Output" and "Torque Sensor 2 Output" on the Techstream display Standard voltage: 2.5 to 4.7 V Turn the steering wheel from its center position to the left full lock position and read the values of "Torque Sensor 1 Output" and "Torque Sensor 2 Output" on the Techstream display. Standard voltage: 0.3 to 2.5 V Check the difference in the values of "Torque Sensor 1 Output" and "Torque Sensor 2 Output". Standard voltage: 0.3 V or less OK : REPLACE POWER STEERING ECU NG : GO TO NEXT STEP
2. CHECK STEERING COLUMN ASSEMBLY (TORQUE SENSOR) Measure the voltage of the ECU. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition P10-6 (TRQV) - P10-8 (TRQG) Power switch is ON (IG) 7.5 to 8.5 V OK : REPLACE POWER STEERING ECU NG : GO TO NEXT STEP
3. CHECK POWER STEERING ECU Measure the voltage of the ECU. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition P10-5 (TRQ1) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel center position 2.3 to 2.7 P10-7 (TRQ2) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel center position 2.3 to 2.7 P10-5 (TRQ1) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel turned to right 2.5 to 4.7 P10-7 (TRQ2) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel turned to right 2.5 to 4.7 P10-5 (TRQ1) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel turned to left 0.3 to 2.5 V P10-7 (TRQ2) - P10-8 (TRQG) Power switch is ON (IG) Steering wheel turned to left 0.3 to 2.5 V OK : REPLACE STEERING COLUMN ASSEMBLY NG : REPLACE POWER STEERING ECU

This DTC does not indicate a malfunction. The power steering ECU outputs this DTC when it determines that the torque sensor zero point calibration has not been performed.

DTC DETECTION CONDITION AND TROUBLE AREA

This DTC does not indicate a malfunction. The power steering ECU outputs this DTC when it determines that the torque sensor zero point calibration has not been completed normally.

DTC DETECTION CONDITION AND TROUBLE AREA

The power steering ECU supplies current to the power steering motor through this circuit.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. CHECK POWER STEERING ECU Turn the power switch ON (IG). Measure the voltage of the ECU. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition P9-1 (M1) - P7-2 (PGND) The steering wheel is turned to the left. Below 1 V P9-1 (M1) - P7-2 (PGND) The steering wheel is turned to the right. 10 to 16 V P9-2 (M2) - P7-2 (PGND) The steering wheel is turned to the left. 10 to 16 V P9-2 (M2) - P7-2 (PGND) The steering wheel is turned to the right. Below 1 V NG : REPLACE POWER STEERING ECU OK : GO TO NEXT STEP
2. CHECK POWER STEERING MOTOR Turn the power switch OFF. Disconnect the P9 power steering ECU connector. Measure the resistance of the wire harness side connector. Standard resistance TERMINALS RESISTANCE SPECIFICATION Tester Connection Specified Condition P9-1 (M1) - P9-2 (M2) 0.04 to 0.1 ohms P9-1 (M1) - Body ground 10 kohms or higher P9-2 (M2) - Body ground 10 kohms or higher NG : REPLACE STEERING COLUMN ASSEMBLY OK : REPLACE POWER STEERING ECU

Fail-safe function operates to stop power assist while DTCs indicating ECU malfunctions are output. However, power assist continues when DTC C1534 is output because it indicates an EEPROM error in the ECU.

DTC DETECTION CONDITION AND TROUBLE AREA

The power steering ECU distinguishes on / off status of the power switch through this circuit.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. INSPECT FUSE (ECU-IG) Remove the ECU-IG fuse from the driver side junction block. Measure the resistance of the fuse. Standard resistance: Below 1 ohms NG : INSPECT FOR SHORT IN ALL COMPONENTS CONNECTED TO FUSE AND REPAIR OR REPLACE THEM IF NEEDED, AND REPLACE FUSE OK : GO TO NEXT STEP
2. CHECK WIRE HARNESS (POWER STEERING ECU - BODY GROUND) Disconnect the P8 power steering ECU connector. Turn the power switch ON (IG). Measure the voltage of the wire harness side connector. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition P8-6 (IG) - Body ground Power switch is ON (IG) 10 to 16 V NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : GO TO NEXT STEP
3. CHECK WIRE HARNESS (POWER STEERING ECU - BODY GROUND) Turn the power switch OFF. Disconnect the P7 power steering ECU connector. Measure the resistance of the wire harness side connector. Standard resistance TERMINALS RESISTANCE SPECIFICATION Tester Connection Specified Condition P7-2 (PGND) - Body ground Below 1 ohms NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : REPLACE POWER STEERING ECU

When a problem occurs in the system, the power source relay (built into the power steering ECU) circuit and the motor relay (built into the power steering ECU) circuit are shut off to stop power assist. It is necessary to replace the ECU when there is a problem in the relay because each relay is built into the ECU.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. INSPECT FUSE (EPS) Remove the EPS H-fuse from the engine room junction block. Measure the resistance of the fuse. Standard resistance: Below 1 ohms NG : INSPECT FOR SHORT IN ALL COMPONENTS CONNECTED TO FUSE AND REPAIR OR REPLACE THEM IF NEEDED, AND REPLACE FUSE OK : GO TO NEXT STEP
2. CHECK WIRE HARNESS (POWER STEERING ECU - BODY GROUND) Disconnect the P7 power steering ECU connector. Measure the voltage of the wire harness side connector. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Specified Condition P7-1 (PIG) - Body ground 10 to 16 V NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : GO TO NEXT STEP
3. CHECK WIRE HARNESS (POWER STEERING ECU - BODY GROUND) Disconnect the P7 power steering ECU connector. Measure the resistance of the wire harness side connector. Standard resistance TERMINALS RESISTANCE SPECIFICATION Tester Connection Specified Condition P7-2 (PGND) - Body ground Below 1 ohms NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : REPLACE POWER STEERING ECU

The power steering ECU outputs this DTC when it determines that assist map is not written in the ECU. It is necessary to replace the power steering ECU when this code is output because this malfunction cannot be repaired.

HINT

The assist map is data written in the power steering ECU to control assisting power. The assist map is selected from four types based on the vehicle specification communication data (designation and grade package information).

DTC DETECTION CONDITION AND TROUBLE AREA

The power steering ECU receives signals from the skid control ECU (ECB ECU) via CAN communication.

DTC DETECTION CONDITION AND TROUBLE AREA

HINT

When 2 or more DTCs starting with [U] are output simultaneously, inspect the connectors and wire harness of each ECU.

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The troubleshooting procedure for a situation when no DTCs are output but a PS warning is always indicated is specified here. The PS warning remains on when there is an open in the IG circuit that inputs power source voltage to the power steering ECU.

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1. CHECK CONNECTOR CONNECTION CONDITION Check the indication condition of the PS warning while wiggling the power steering ECU connector and wire harness up and down, and right and left. OK : Warning indication does not change. NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : GO TO NEXT STEP
2. INSPECT CAN COMMUNICATION SYSTEM Using the Techstream (with CAN VIM), check for DTCs and confirm that there are no problems in the CAN communication system. OK : DTCs are not output. NG : GO TO CAN COMMUNICATION SYSTEM OK : GO TO NEXT STEP
3. INSPECT MULTIPLEX COMMUNICATION SYSTEM (BEAN) Using the Techstream (with CAN VIM), check for DTCs and confirm that there are no problems in the multiplex communication system (BEAN). OK : DTCs are not output. NG : GO TO MULTIPLEX COMMUNICATION SYSTEM OK : GO TO NEXT STEP
4. CHECK WIRE HARNESS (POWER STEERING ECU - BATTERY) Disconnect the P7 and P8 power steering ECU connectors. Turn the power switch ON (IG). Measure the voltage of the wire harness side connectors. Standard voltage TERMINALS VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition P8-6 (IG) - P7-2 (PGND) Power switch ON (IG) 10 to 16 V NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : GO TO NEXT STEP
5. REPLACE POWER STEERING ECU NEXT
6. CHECK PS WARNING ON MULTI-DISPLAY Check for the PS warning indication on the multi-display. OK : PS warning is not indicated. OK : END NG : REPLACE MULTI-DISPLAY

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1. PLACE FRONT WHEELS FACING STRAIGHT AHEAD
2. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation. NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected. See «INITIALIZATION»(ref-289861-S01642846932008070800000).
3. REMOVE COLUMN HOLE COVER SILENCER SHEET (See «REMOVAL»(ref-289864-S22159702112008070800000) )
4. SEPARATE STEERING SLIDING YOKE SUB-ASSEMBLY Fix the steering wheel with the seat belt in order to prevent rotation and damage to the spiral cable. Put matchmarks in the sliding yoke and intermediate shaft. Loosen the bolt labeled A and remove the bolt labeled B to separate the sliding yoke.
5. DISCONNECT NO. 1 STEERING COLUMN HOLE COVER SUB-ASSEMBLY Remove the clip labeled A and disconnect the hole cover from the body. NOTE: Do not damage the clip labeled B.
6. REMOVE FRONT WHEELS
7. DISCONNECT NO. 2 TIE ROD END SUB-ASSEMBLY (See «REMOVAL»(ref-289884-S34788974572008070800000) )
8. DISCONNECT NO. 1 TIE ROD END SUB-ASSEMBLY HINT: Use the same procedure described for the No. 2 tie rod end.
9. REMOVE FRONT STABILIZER LINK ASSEMBLY LH (See «REMOVAL»(ref-289881-S03435383412008070800000) )
10. REMOVE FRONT STABILIZER LINK ASSEMBLY RH HINT: Use the same procedure described for the LH.
11. REMOVE FRONT NO. 1 STABILIZER BRACKET LH (See «REMOVAL»(ref-289881-S03435383412008070800000) )
12. REMOVE FRONT NO. 1 STABILIZER BRACKET RH HINT: Use the same procedure described for the LH.
13. REMOVE STEERING INTERMEDIATE SHAFT Move the No. 1 column hole cover to the upper side of the vehicle and put matchmarks on the intermediate shaft and steering gear. NOTE: Do not damage the No. 1 hole cover when moving it. Remove the bolt and remove the intermediate shaft from the inside of the vehicle. Remove the No. 1 column hole cover from the steering gear. NOTE: Do not damage the No. 1 hole cover clip.
14. REMOVE STEERING GEAR ASSEMBLY Remove the 4 bolts and steering gear from the left side of the vehicle. HINT: Be careful not to hit the stabilizer bar when removing the steering gear.

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1. FIX STEERING GEAR ASSEMBLY Using SST wrapped with protective tape, secure the steering gear in a vise. SST 09612-00012 HINT: Remove and reinstall the SST as needed.
2. REMOVE TIE ROD END SUB-ASSEMBLY LH Put matchmarks on the tie rod end LH and rack end. Remove the tie rod end LH and lock nut.
3. REMOVE TIE ROD END SUB-ASSEMBLY RH HINT: Use the same procedure described for the LH.
4. REMOVE STEERING RACK BOOT CLIP Using pliers, remove the 2 rack boot clips (for RH and LH).
5. REMOVE NO. 2 STEERING RACK BOOT CLAMP Using a screwdriver, unstake and remove the clamp. NOTE: Do not damage the boot.
6. REMOVE NO. 1 STEERING RACK BOOT CLAMP HINT: Use the same procedures described for the No. 2 rack boot clamp.
7. REMOVE NO. 2 STEERING RACK BOOT
8. REMOVE NO. 1 STEERING RACK BOOT
9. REMOVE STEERING RACK END SUB-ASSEMBLY Using 2 SST, remove the rack end (for LH side). SST 09922-10010 NOTE: Use SST in the correct direction as shown in the illustration. Securely hold the steering rack. Using 2 SST, hold the steering rack LH side and remove the rack end (for RH side). SST 09922-10010 NOTE: Use SST in the correct direction (Scheme 27) Securely hold the steering rack.

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1. INSPECT TIE ROD END SUB-ASSEMBLY LH Secure the tie rod end LH boll join in a vise through aluminum plates. NOTE: Do not overtighten the vise. Install the castle nut to the stud bolt. Flip the ball joint back and forth 5 times or more. Set a torque wrench to the nut, turn the ball joint continuously at a rate of 3 to 5 seconds per turn, and check the turning torque on the 5th turn. Standard turning torque: 2.0 N*m (20.4 kgf*cm, 18 in. lbf) or less If turning torque is out of specification, replace the tie rod end LH with a new one.
2. INSPECT TIE ROD END SUB-ASSEMBLY RH HINT: Use the same procedures described for the LH side.
3. INSPECT TOTAL PRELOAD Using SST, inspect the total preload. SST 09616-00011 Standard total preload (turning): 0.6 to 1.2 N*m (6.2 to 12.2 kgf*cm, 5 to 11 in.*lbf) NOTE: Inspect around the steering rack center position. If the total preload is out of specification, replace the steering gear with a new one.

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1. INSTALL STEERING RACK END SUB-ASSEMBLY Fill up the ball joints of the RH and LH rack ends with molybdenum disulfide lithium base grease. Using 2 SST, hold the steering rack LH side and install the rack end (for RH side). SST 09922-10010 Torque: 60 N*m (612 kgf*cm, 44 ft.*lbf) NOTE: Use a torque wrench with a fulcrum length of 345 mm (13.58 in.). Use SST in the correct direction as shown in the illustration. Securely hold the steering rack. Using 2 SST, install the rack end (for LH side). SST 09922-10010 Torque: 60 N*m (612 kgf*cm, 44 ft.*lbf) NOTE: Use a torque wrench with a fulcrum length of 345 mm (13.58 in.). Use SST in the correct direction (Scheme 31) Securely hold the steering rack.
2. INSTALL NO. 2 STEERING RACK BOOT Apply silicon grease to the inside of the small opening of the boot. Install the boot in the groove on the rack housing. NOTE: Make sure that the boot is not twisted.
3. INSTALL NO. 1 STEERING RACK BOOT HINT: Use the same procedures described for the No. 2 boot.
4. INSTALL NO. 2 STEERING RACK BOOT CLAMP Install a new clamp to the boot. NOTE: Do not damage the boot. While pushing SST to the rack housing, pinch the clamp so that the clearance is within specification. SST 09521-24010 Standard clearance: 3.0 mm (0.12 in.) or less NOTE: Make sure that the boot is not twisted.
5. INSTALL NO. 1 STEERING RACK BOOT CLAMP HINT: Use the same procedures described for the No. 2 rack boot clamp.
6. INSTALL STEERING RACK BOOT CLIP Using pliers, install the 2 rack boot clips to the RH and LH rack boots.
7. INSPECT STEERING GEAR ASSEMBLY Using SST, turn the pinion shaft and check that the RH and LH rack boots expand and contract smoothly, reinstall it with a new rack boot clamp. SST 09616-00011 If the rack boot does not expand and contract smoothly, reinstall it with a new rack boot clamp.
8. INSTALL TIE ROD END SUB-ASSEMBLY LH Screw the lock nut and tie rod end LH on the rack end unit the matchmarks are aligned and temporarily tighten the lock nut. HINT: Fully tighten the lock nut after adjusting toe-in.
9. REMOVE TIE ROD END SUB-ASSEMBLY RH HINT: Use the same procedures described for the LH side.

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1. INSTALL STEERING GEAR ASSEMBLY Install the steering gear from the left side of the vehicle. HINT: Be careful not to hit the stabilizer bar when installing the steering gear. Install the No. 1 column hole cover to the steering gear. Install the steering gear to the crossmember with the 4 bolts. Torque: 58 N*m (591 kgf*cm, 43 ft.*lbf)
2. INSTALL STEERING INTERMEDIATE SHAFT Move the No. 1 column hole cover to the upper side of the vehicle, align the matchmarks, and install the intermediate shaft from the inside of the vehicle. NOTE: Do not damage the No. 1 hole cover when moving it. Install the bolt. Torque: 35 N*m (360 kgf*cm, 26 ft.*lbf) Fit the recessed part on the No. 1 column hole cover to the steering gear. NOTE: Make sure that the No. 1 hole cover is securely installed.
3. INSTALL FRONT NO. 1 STABILIZER BRACKET LH (See «INSTALLATION»(ref-289881-S08162123622008070800000) )
4. INSTALL FRONT NO. 1 STABILIZER BRACKET RH HINT: Use the same procedures described for the LH side.
5. INSTALL FRONT STABILIZER LINK ASSEMBLY LH (See «INSTALLATION»(ref-289881-S08162123622008070800000) )
6. INSTALL FRONT STABILIZER LINK ASSEMBLY RH HINT: Use the same procedures described for the LH side.
7. CONNECT NO. 1 TIE ROD END SUB-ASSEMBLY (See «INSTALLATION»(ref-289884-S01190997642008070800000) )
8. CONNECT NO. 2 TIE ROD END SUB-ASSEMBLY HINT: Use the same procedures described for the No. 1 tie rod end.
9. INSTALL FRONT WHEEL Torque: 103 N*m (1,050 kgf*cm, 76 ft.*lbf)
10. INSTALL NO. 1 STEERING COLUMN HOLE COVER SUB-ASSEMBLY Install the clip labeled B to the vehicle body and install the No. 1 column hole cover to the vehicle body with the clip labeled A. NOTE: Make sure that the lip of the No. 1 hole cover fits on the dash panel correctly.
11. INSTALL STEERING SLIDING YOKE SUB-ASSEMBLY
12. INSTALL STEERING SLIDING YOKE SUB-ASSEMBLY Align the matchmarks and install the sliding yoke to the intermediate shaft with the bolt labeled B. Torque: 35 N*m (360 kgf*cm, 26 ft.*lbf) Tighten the bolt labeled A. Torque: 35 N*m (360 kgf*cm, 26 ft.*lbf)
13. INSTALL COLUMN HOLE COVER SILENCER SHEET
14. REPLACE FRONT WHEELS FACING STRAIGHT AHEAD
15. INSPECT AND ADJUST FRONT WHEEL ALIGNMENT Inspect and adjust the front wheel alignment (see «FRONT WHEEL ALIGNMENT»(ref-289881-S21248125902008070800000) ).
16. PERFORM STEERING ANGLE SENSOR ZERO POINT CALIBRATION Perform calibration, see «CALIBRATION»(ref-289882-S08061411722008070800000). Perform initialization (see «INITIALIZATION»(ref-289861-S01642846932008070800000) ). NOTE: Certain systems need to be initialized after disconnecting and reconnecting the cable from the negative (-) battery terminal.

See also:
• ECM