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Power Steering (Diagnostic Codes & Circuit Tests): Overview Lexus RX III

Manual & Power Steering 7 illustrations ~1214 words

Scheme 45

Scheme 45: ON-VEHICLE INSPECTION
  1. CHECK STEERING EFFORT (TORQUE) NOTE: Some of these service operations may affect the SRS airbags. Read the precautionary notices concerning the SRS airbag system before servicing. Stop the vehicle on a level, paved surface and align the wheels straight ahead. Disconnect the cable from the negative (-) battery terminal. WARNING: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system. NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected. Refer to «INITIALIZATION»(ref-400649-S12881576452011051800000) . w/ Navigation System for HDD After the engine switch is turned off, the display and navigation module display (HDD navigation system) records various types of memory and settings. As a result, after turning the engine switch off, make sure to wait at least 60 seconds before disconnecting the cable from the negative (-) battery terminal. Remove the steering pad. Refer to «REMOVAL»(ref-400651-S01272841122011051800000) . Connect the cable to the negative (-) battery terminal. Using a torque wrench, check that the steering wheel set nut is properly tightened. Torque: 50 N*m (510 kgf*cm, 37 ft.*lbf) Turn the engine switch on (IG) so that the power steering is available. Turn the steering wheel 90 degrees to the right and check the steering effort (torque) while continuing to turn it further in the same direction. Steering effort (Reference) 6.9 N*m (70 kgf*cm, 61 in.*lbf) or less Align the front wheels facing straight ahead. Disconnect the cable from the negative (-) battery terminal. WARNING: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system. Install the steering pad. Refer to «INSTALLATION»(ref-400651-S20532233812011051800000) . Connect the cable to the negative (-) battery terminal. NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected. Refer to «INITIALIZATION»(ref-400649-S12881576452011051800000) . w/ Navigation System for HDD After the engine switch is turned off, the display and navigation module display (HDD navigation system) records various types of memory and settings. As a result, after turning the engine switch off, make sure to wait at least 60 seconds before disconnecting the cable from the negative (-) battery terminal. Clear the DTCs. Refer to «DTC CHECK / CLEAR»(ref-400869-S14137993302011051800000) . Inspect the airbag warning light. Refer to «DIAGNOSIS SYSTEM»(ref-400811-S16959918682011051800000) .

DESCRIPTION

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

DTC No.DTC Detection ConditionTrouble Area
C1511Torque sensor (TRQ1) signal error or stopSteering column assembly (torque sensor) Power steering ECU
C1512Torque sensor (TRQ2) signal error or stop
C1513Deviation between torque sensors TRQ1 and TRQ2 exceeds specified value
C1514Torque sensor power source voltage error
C1517Temporary control due to malfunction related to torque sensor continues for long time

Scheme 46

Scheme 46: WIRING DIAGRAM

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

DTC No.DTC Detection ConditionTrouble Area
C1511Torque sensor (TRQ1) signal error or stopSteering column assembly (torque sensor) Power steering ECU
C1512Torque sensor (TRQ2) signal error or stop
C1513Deviation between torque sensors TRQ1 and TRQ2 exceeds specified value
C1514Torque sensor power source voltage error
C1517Temporary control due to malfunction related to torque sensor continues for long time

These DTCs do not indicate a malfunction. The power steering ECU stores these DTCs when it determines that the rotation angle sensor value initialization and torque sensor zero point calibration have not been performed.

DTC No.DTC Detection ConditionTrouble Area
C1515This DTC is detected when torque sensor zero point calibration has not been performed.There is no malfunction if this DTC is not output again after performing torque sensor zero point calibration.
C1525This DTC is detected when rotation angle sensor value initialization has not been performed.There is no malfunction if this DTC is not output again after performing rotation angle sensor value initialization.

These DTCs do not indicate a malfunction. The power steering ECU stores these DTCs when it determines that the rotation angle sensor value initialization and torque sensor zero point calibration have not been performed.

DTC No.DTC Detection ConditionTrouble Area
C1515This DTC is detected when torque sensor zero point calibration has not been performed.There is no malfunction if this DTC is not output again after performing torque sensor zero point calibration.
C1525This DTC is detected when rotation angle sensor value initialization has not been performed.There is no malfunction if this DTC is not output again after performing rotation angle sensor value initialization.

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

DTC No.DTC Detection ConditionTrouble Area
C1516Torque sensor zero point calibration is incomplete due to the steering wheel being touched during calibration.There is no malfunction if this DTC is not output again after clearing the DTCs and torque sensor calibration value, and performing zero point calibration.
C1526Rotation angle sensor value initialization is incomplete due to the steering wheel being touched during calibration.There is no malfunction if this DTC is not output again after clearing the DTCs and torque sensor calibration value, and performing rotation angle sensor value initialization.

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

DTC No.DTC Detection ConditionTrouble Area
C1516Torque sensor zero point calibration is incomplete due to the steering wheel being touched during calibration.There is no malfunction if this DTC is not output again after clearing the DTCs and torque sensor calibration value, and performing zero point calibration.
C1526Rotation angle sensor value initialization is incomplete due to the steering wheel being touched during calibration.There is no malfunction if this DTC is not output again after clearing the DTCs and torque sensor calibration value, and performing rotation angle sensor value initialization.

If the power steering ECU detects these DTCs, it will shut off the motor relay circuit (built into the power steering ECU) and stop power assist. However, power assist continues if DTC C1533 or C1534 is stored.

DTC No.DTC Detection ConditionTrouble Area
C1521Motor overcurrentPower steering ECU
C1531ECU internal malfunction (CPU malfunction)Power steering ECU
C1532ECU internal malfunction (Peripheral circuit malfunction)Power steering ECU
C1533ECU internal malfunction (Substrate temperature sensor malfunction)Power steering ECU
C1534ECU internal malfunction (EEPROM error)Power steering ECU
C1554Power source relay circuit malfunctionPower steering ECU

If the power steering ECU detects these DTCs, it will shut off the motor relay circuit (built into the power steering ECU) and stop power assist. However, power assist continues if DTC C1533 or C1534 is stored.

DTC No.DTC Detection ConditionTrouble Area
C1521Motor overcurrentPower steering ECU
C1531ECU internal malfunction (CPU malfunction)Power steering ECU
C1532ECU internal malfunction (Peripheral circuit malfunction)Power steering ECU
C1533ECU internal malfunction (Substrate temperature sensor malfunction)Power steering ECU
C1534ECU internal malfunction (EEPROM error)Power steering ECU
C1554Power source relay circuit malfunctionPower steering ECU

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

DTC No.DTC Detection ConditionTrouble Area
C1522Motor current sensor malfunctionSteering column assembly (Power steering motor) Power steering ECU
C1523Excessively large current deviation
C1524Short (or open) in motor circuit or abnormal voltage or current in motor circuit
C1555Motor relay circuit malfunction

Scheme 47

Scheme 47: WIRING DIAGRAM

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

DTC No.DTC Detection ConditionTrouble Area
C1522Motor current sensor malfunctionSteering column assembly (Power steering motor) Power steering ECU
C1523Excessively large current deviation
C1524Short (or open) in motor circuit or abnormal voltage or current in motor circuit
C1555Motor relay circuit malfunction

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

DTC No.DTC Detection ConditionTrouble Area
C1528Motor rotation angle sensor malfunctionMotor rotation angle sensor (built into steering column assembly) Power steering ECU

Scheme 48

Scheme 48: WIRING DIAGRAM

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

DTC No.DTC Detection ConditionTrouble Area
C1528Motor rotation angle sensor malfunctionMotor rotation angle sensor (built into steering column assembly) Power steering ECU

The power steering ECU receives vehicle speed signals from the brake actuator assembly (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.

DTC No.DTC Detection ConditionTrouble Area
C1541This DTC is detected when vehicle speed signals via CAN communication are cut off for 3 seconds or more.Speed sensor circuit Brake actuator assembly (Skid control ECU) CAN communication system Power steering ECU

The power steering ECU receives vehicle speed signals from the brake actuator assembly (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.

DTC No.DTC Detection ConditionTrouble Area
C1541This DTC is detected when vehicle speed signals via CAN communication are cut off for 3 seconds or more.Speed sensor circuit Brake actuator assembly (Skid control ECU) CAN communication system Power steering ECU

The power steering ECU distinguishes the engine switch status as on (IG) or off through the IG power source circuit.

DTC No.DTC Detection ConditionTrouble Area
C1551IG power source circuit malfunction inside ECUECU-IG1 No. 1 fuse IG power source circuit Power steering ECU

Scheme 49

Scheme 49: WIRING DIAGRAM

The power steering ECU distinguishes the engine switch status as on (IG) or off through the IG power source circuit.

DTC No.DTC Detection ConditionTrouble Area
C1551IG power source circuit malfunction inside ECUECU-IG1 No. 1 fuse IG power source circuit Power steering ECU

If a problem occurs in the power steering system, the power source relay circuit is shut off to stop the power assist.

DTC No.DTC Detection ConditionTrouble Area
C1552PIG power source circuit malfunction inside ECUEPS fuse PIG power source circuit Power steering ECU

Scheme 50

Scheme 50: WIRING DIAGRAM

If a problem occurs in the power steering system, the power source relay circuit is shut off to stop the power assist.

DTC No.DTC Detection ConditionTrouble Area
C1552PIG power source circuit malfunction inside ECUEPS fuse PIG power source circuit Power steering ECU

The power steering ECU stores 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 to control the degree of assistance. The assist map is selected based on the vehicle's specified communication data.

DTC No.DTC Detection ConditionTrouble Area
C1581Assist map not written in power steering ECUPower steering ECU CAN communication system ECM

The power steering ECU stores 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 to control the degree of assistance. The assist map is selected based on the vehicle's specified communication data.

DTC No.DTC Detection ConditionTrouble Area
C1581Assist map not written in power steering ECUPower steering ECU CAN communication system ECM

When an incorrect ECM is installed after the assist map has been recorded in the power steering ECU, then DTC C1582 is stored because the data does not match the vehicle specifications.

DTC No.DTC Detection ConditionTrouble Area
C1582Assist map number mismatchPower steering ECU CAN communication system ECM

When an incorrect ECM is installed after the assist map has been recorded in the power steering ECU, then DTC C1582 is stored because the data does not match the vehicle specifications.

DTC No.DTC Detection ConditionTrouble Area
C1582Assist map number mismatchPower steering ECU CAN communication system ECM

The power steering ECU receives signals from the ECM and the brake actuator assembly (skid control ECU) via the CAN communication system.

DTC No.DTC Detection ConditionTrouble Area
U0100Lost communication with ECM/PCM "A"CAN communication system ECM
U0129Lost communication with brake system control moduleCAN communication system Brake actuator assembly (Skid control ECU)
U1104Lost communication with driving support ECUCAN communication system Driving support ECU

The power steering ECU receives signals from the ECM and the brake actuator assembly (skid control ECU) via the CAN communication system.

DTC No.DTC Detection ConditionTrouble Area
U0100Lost communication with ECM/PCM "A"CAN communication system ECM
U0129Lost communication with brake system control moduleCAN communication system Brake actuator assembly (Skid control ECU)
U1104Lost communication with driving support ECUCAN communication system Driving support ECU

If the power steering ECU detects a malfunction, the P/S warning light comes on. At this time, the power steering ECU stores a DTC in its memory.

Scheme 51

Scheme 51: WIRING DIAGRAM

If the power steering ECU detects a malfunction, the P/S warning light comes on. At this time, the power steering ECU stores a DTC in its memory.