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Power Steering (Diagnostic Codes & Circuit Tests): Overview Lexus HS I

Manual & Power Steering 6 illustrations ~391 words

DESCRIPTION

The torque sensor converts the rotation torque input from the steering wheel into electric signals and sends them to the power steering ECU.

DTC No.DTC Detection ConditionTrouble Area
C1511Torque sensor malfunctionSteering column assembly (Torque sensor) Power steering ECU
C1512
C1513
C1514
C1517

Scheme 45

Scheme 45: WIRING DIAGRAM

These DTCs do not indicate a malfunction. The power steering ECU outputs 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 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 outputs 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 output.

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

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

DTC No.DTC Detection ConditionTrouble Area
C1522Motor current sensor malfunctionSteering column assembly 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 46

Scheme 46: 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 malfunctionSteering column assembly (Motor rotation angle sensor) Power steering ECU

Scheme 47

Scheme 47: WIRING DIAGRAM

The power steering ECU 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.

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 Skid control ECU CAN communication system Power steering ECU

The power steering ECU distinguishes the power 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-IG No. 1 fuse IG power source circuit Power steering ECU

Scheme 48

Scheme 48: WIRING DIAGRAM

When 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
C1554Power source relay circuit malfunctionEPS fuse PIG power source circuit Power steering ECU

Scheme 49

Scheme 49: WIRING DIAGRAM

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

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

When an incorrect hybrid vehicle control ECU 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 Hybrid vehicle control ECU

The power steering ECU receives signals from the skid control ECU, hybrid vehicle control ECU and driving support ECU via the CAN communication system.

DTC No.DTC Detection ConditionTrouble Area
U0129Lost communication with brake system control moduleCAN communication system Skid control ECU
U0293Lost communication with hybrid vehicle control ECUCAN communication system Hybrid vehicle 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 50

Scheme 50: WIRING DIAGRAM

See also:
REMOVAL