Power Steering: Overview Lexus IS II

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.

DIAGNOSTIC TROUBLE CODE TABLE

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1. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - TORQUE SENSOR) Disconnect the C4 connector from the power steering ECU assembly. Disconnect the C1 connector from the torque sensor. Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S42840603032006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester connection (Symbols) Condition Specified condition C1-1 (INCS) - C4-10 (INCS) Always Below 1 ohms C1-2 (INSN) - C4-9 (INSN) Always Below 1 ohms C1-4 (TRQV) - C4-4 (TRQV) Always Below 1 ohms C1-5 (OUCS) - C4-12 (OUCS) Always Below 1 ohms C1-6 (OUSN) - C4-11 (OUSN) Always Below 1 ohms C1-7 (TQG2) - C4-13 (TQG2) Always Below 1 ohms C1-8 (TQG1) - C4-6 (TQG1) Always Below 1 ohms C1-1 (INCS) - Body ground Always 10 k ohms or higher C1-2 (INSN) - Body ground Always 10 k ohms or higher C1-4 (TRQV) - Body ground Always 10 k ohms or higher C1-5 (OUCS) - Body ground Always 10 k ohms or higher C1-6 (OUSN) - Body ground Always 10 k ohms or higher C1-7 (TQG2) - Body ground Always 10 k ohms or higher C1-8 (TQG1) - Body ground Always 10 k ohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
2. INSPECT POWER STEERING GEAR ASSEMBLY (TORQUE SENSOR) Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S23768180592006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester connection (Symbols) Condition Specified condition C1-1 (INCS) - C1-7 (TQG2) Always 90 to 170 ohms C1-2 (INSN) - C1-7 (TQG2) Always 300 to 430 ohms C1-4 (TRQV) - C1-8 (TQG1) Always 4 to 14 ohms C1-5 (OUCS) - C1-7 (TQG2) Always 90 to 170 ohms C1-6 (OUSN) - C1-7 (TQG2) Always 300 to 430 ohms NOTE: If replacing the power steering gear assembly, clear the rotation angle sensor calibration value, initialize the rotation angle sensor value, and calibrate the torque sensor zero point (See ). NG: REPLACE POWER STEERING GEAR ASSEMBLY OK: Go To Next Step
3. REPLACE POWER STEERING ECU ASSEMBLY Replace the power steering ECU assembly (See «REMOVAL»(ref-235574-S30484137362006062400000) ). Go to next Step
4. INITIALIZE ROTATION ANGLE SENSOR AND CALIBRATE TORQUE SENSOR ZERO POINT Initialize the rotation angle sensor value and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). Go to next Step
5. RECONFIRM DTC Check for DTCs (See «DTC CHECK / CLEAR»(ref-235574-S32212763012006062400000) ). Result RESULT REFERENCE TABLE DTC Condition Proceed to DTC is not output A DTC C1511, C1512, or C1513 is output B NOTE: If replacing the power steering gear assembly, clear the rotation angle sensor calibration value, initialize the rotation angle sensor value, and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). B: REPLACE POWER STEERING GEAR ASSEMBLY A: END

These DTCs do not indicate a malfunction. The power steering ECU assembly outputs these DTCs when it determines that rotation angle sensor value initialization and torque sensor zero point calibration have not been performed. When IG terminal voltage is 9 V or less rotation angle sensor initialization and torque sensor zero point calibration cannot be performed.

DIAGNOSTIC TROUBLE CODE TABLE

These DTCs do not indicate a malfunction. The power steering ECU assembly outputs these DTCs when it determines that rotation angle sensor value initialization and torque sensor zero point calibration are incomplete.

DIAGNOSTIC TROUBLE CODE TABLE

If the power steering ECU assembly detects these DTCs, it will shut off the motor current sensor, power source relay, motor relay circuit (built into the power steering ECU assembly) and stop power assistance.

However , power assistance will continue if DTC C1533 or C1534 is output.

DIAGNOSTIC TROUBLE CODE TABLE

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

DIAGNOSTIC TROUBLE CODE TABLE

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1. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - POWER STEERING MOTOR) Disconnect the C5 connector from the power steering ECU assembly. Disconnect the C3 connector from the power steering motor. Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S01261852222006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester Connection Condition Specified condition C5-1 (V) - C3-2 (V) Always Below 1 ohms C5-2 (U) - C3-3 (U) Always Below 1 ohms C5-3 (W) - C3-1 (W) Always Below 1 ohms C5-1 (V) - Body ground Always 10 k ohms or higher C5-2 (U) - Body ground Always 10 k ohms or higher C5-3 (W) - Body ground Always 10 k ohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
2. INSPECT POWER STEERING GEAR ASSEMBLY (POWER STEERING MOTOR) Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S01268217152006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester Connection Condition Specified condition C3-3 (U) - C3-2 (V) Always Below 1 ohms C3-2 (V) - C3-1 (W) Always Below 1 ohms C3-1 (W) - C3-3 (U) Always Below 1 ohms C3-3 (U) - Motor body Always 10 k ohms or higher C3-2 (V) - Motor body Always 10 k ohms or higher C3-1 (W) - Motor body Always 10 k ohms or higher NOTE: If replacing the power steering gear assembly, clear the rotation angle sensor value calibration value, initialize the rotation angle sensor, and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). NOTE: If replacing the power steering ECU assembly, initialize the rotation angle sensor value and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). NG: REPLACE POWER STEERING GEAR ASSEMBLY OK: REPLACE POWER STEERING ECU ASSEMBLY

The motor rotation angle sensor detects the motor rotation angle and sends this information to the power steering ECU assembly.

DIAGNOSTIC TROUBLE CODE TABLE

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1. CHECK POWER STEERING EARTH WIRE (POWER STEERING GEAR ASSEMBLY - BODY GROUND) Check the installation condition of the power steering earth wire connected to the power steering gear assembly. OK: The power steering earth wire is securely installed to the power steering gear assembly and body ground. NG: REINSTALL POWER STEERING EARTH WIRE OK: Go To Next Step
2. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - MOTOR ROTATION ANGLE SENSOR) Disconnect the C2 connector from the power steering gear assembly. Disconnect the C4 connector from the power steering ECU. Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S34337571442006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester connection symbols) Condition Specified condition C2-1 (RZSN) - C4-7 (RZSN) Always Below 1 ohms C2-2 (RZG) - C4-1 (RZG) Always Below 1 ohms C2-3 (RZV) - C4-3 (RZV) Always Below 1 ohms C2-4 (RZCS) - C4-8 (RZCS) Always Below 1 ohms C2-1 (RZSN) - Body ground Always 10 k ohms or higher C2-2 (RZG) - Body ground Always 10 k ohms or higher C2-3 (RZV) - Body ground Always 10 k ohms or higher C2-4 (RZCS) - Body ground Always 10 k ohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
3. INSPECT POWER STEERING GEAR ASSEMBLY (MOTOR ROTATION ANGLE SENSOR) Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S36145316902006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester connection (Symbols) Condition Specified condition C2-1 (RZSN) - C2-2 (RZG) Always 50 to 140 ohms C2-3 (RZV) - C2-2 (RZG) Always 50 to 140 ohms C2-4 (RZCS) - C2-2 (RZG) Always 15 to 45 ohms NOTE: If replacing the power steering gear assembly, clear the rotation angle sensor calibration value, initialize the rotation angle sensor value, and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). NG: REPLACE POWER STEERING GEAR ASSEMBLY OK: Go To Next Step
4. REPLACE POWER STEERING ECU ASSEMBLY Replace the power steering ECU assembly (See «REMOVAL»(ref-235574-S30484137362006062400000) ).
5. INITIALIZE ROTATION ANGLE SENSOR AND CALIBRATE TORQUE SENSOR ZERO POINT Initialize the rotation angle sensor value and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ).
6. RECONFIRM DTC Check for DTCs (See «DTC CHECK / CLEAR»(ref-235574-S32212763012006062400000) ). Result RESULT REFERENCE TABLE DTC Condition Proceed to DTC is not output A DTC C1528 is output B NOTE: If replacing the power steering gear assembly, clear the rotation angle sensor calibration value, initialize the rotation angle sensor value, and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). B: REPLACE POWER STEERING GEAR ASSEMBLY A: END

The power steering ECU assembly receives vehicle speed signals from the skid control ECU via CAN communication. The ECU provides appropriate assisting force in accordance with the vehicle speed, based on the signals.

If the ECU detects this DTC, it adjusts the amount of power assistance for a speed of 100 km/h (62 mph) and continues the system control.

DIAGNOSTIC TROUBLE CODE TABLE

If the power steering ECU assembly determines that there is a malfunction in the IG circuit inside the ECU, it outputs this DTC. This DTC is not output when there is an open circuit in the wire harness connected to terminal IG or a battery voltage drop.

DIAGNOSTIC TROUBLE CODE TABLE

This circuit supplies power to drive the power steering motor.

DIAGNOSTIC TROUBLE CODE TABLE

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1. INSPECT FUSE (EPS FUSE) Remove the EPS fuse from the engine room relay block. Check for continuity of the EPS fuses. OK: Continuity NG: REPLACE FUSE OK: Go To Next Step
2. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - BATTERY) Disconnect the A31 connector from the power steering ECU assembly. Measure the voltage according value(s) in «STANDARD VOLTAGE REFERENCE TABLE»(ref-235574-S07552914162006062400000) . Standard voltage STANDARD VOLTAGE REFERENCE TABLE Tester Connection Condition Specified condition A31-4 (PIG) - Body ground Always 10 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
3. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - BODY GROUND) Measure the resistance according value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S20326151262006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester Connection Condition Specified condition A31-5 (PGND) - Body ground Always Blow 1 ohms NOTE: If replacing the power steering ECU assembly, initialize the rotation angle sensor value and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE POWER STEERING ECU ASSEMBLY

The power steering ECU assembly outputs this DTC when it determines that the assist map is not written in the ECU.

HINT

The assist map is data written in the power steering ECU assembly to control the degree of assistance.

The assist map is selected based on the vehicle's specified communication data (designation and grade package information).

DIAGNOSTIC TROUBLE CODE TABLE

The power steering ECU assembly receives signals from the ECM, skid control ECU, and steering control ECU via CAN communication.

DIAGNOSTIC TROUBLE CODE TABLE

HINT

1. When two or more DTCs starting with "U " are output simultaneously, inspect the connectors and wire harness of each ECU.
2. If the power steering ECU assembly detects DTC U0121 only, it adjusts the amount of power assistance for a speed of 100 km/h (62 mph) and continues system control.

The power steering ECU is connected to the combination meter via CAN and multiplex communications. If any of the following are detected, the PS warning light remains on.

1. The power steering ECU connectors are disconnected from the power steering ECU.
2. There is a malfunction in the power steering ECU internal circuit.
3. There is an open in the harness between the combination meter and power steering ECU assembly.

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1. CHECK HARNESS AND CONNECTOR Check the indication condition of the PS warning light while by wiggling the power steering ECU assembly connector and wire harness up and down, and right and left. OK: PS warning light indication condition does not change. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
2. INSPECT CAN COMMUNICATION SYSTEM Using the intelligent tester, 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»(ref-235565-S22980917632006062400000) OK: Go To Next Step
3. INSPECT MULTIPLEX COMMUNICATION SYSTEM Using the intelligent tester, 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»(ref-235578-S20958542052006062400000) OK: Go To Next Step
4. INSPECT FUSE Remove the ECU-IG LH fuse from the cowl side J/B LH. Check for continuity of the ECU-IG LH fuse. OK: Below 1 ohms NG: REPLACE FUSE OK: Go To Next Step
5. INSPECT POWER STEERING ECU ASSEMBLY Disconnect the A31 connector from the power steering ECU assembly. Measure the voltage according to the value(s) in «STANDARD VOLTAGE REFERENCE TABLE»(ref-235574-S31947650542006062400000) . Standard voltage STANDARD VOLTAGE REFERENCE TABLE Tester Connection Condition Specified condition A31-9 (IG) - Body ground Engine switch on (IG) 10 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
6. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - BODY GROUND) Measure the resistance according to the value(s) in «STANDARD RESISTANCE REFERENCE TABLE»(ref-235574-S10116002012006062400000) . Standard resistance STANDARD RESISTANCE REFERENCE TABLE Tester Connection Condition Specified condition A31-5 (PGND) - Body ground Engine switch on (IG) Below 1 ohms NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step
7. INSPECT COMBINATION METER ASSEMBLY Connect the intelligent tester (with CAN VIM ) to the DLC3. Turn the engine switch on (IG). Perform the ACTIVE TEST according to the display on the tester. METER: METER SPECIFICATION Item Test Details Diagnostic Note EPS INDIC PS indicator light OFF/ON - OK: PS indicator light comes on. NOTE: If replacing the power steering ECU assembly, initialize the rotation angle sensor value and calibrate the torque sensor zero point (See «CALIBRATION»(ref-235574-S14191448492006062400000) ). NG: REPLACE COMBINATION METER ASSEMBLY OK: REPLACE POWER STEERING ECU ASSEMBLY

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