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Variable Gear Ratio Steering System (Diagnostic Codes & Symptom Tests): Overview Lexus GS III facelift

Electronic Steering 21 illustrations ~1867 words

DESCRIPTION

If the steering control ECU or steering actuator is replaced, or if the tie-rod ends are adjusted, VGRS system calibration is required. If the steering control ECU detects that steering angle adjustment is incomplete, it will store DTC C1591/51.

DTC No.DTC Detecting ConditionProcedure
C1591/51The steering control ECU detects that steering angle adjustment is incomplete.There is no malfunction if this DTC is not output again after performing VGRS system calibration.

The steering control ECU first checks the actuator angle neutral position calibration flag after entering test mode. If the ECU detects that steering actuator angle neutral position calibration is incomplete twice, it will store DTC C1592/52.

DTC No.DTC Detecting ConditionTrouble Area
C1592/52The steering control ECU detects that steering actuator angle neutral position calibration is incomplete, twice.Steering actuator Steering control ECU

If the steering control ECU detects a steering actuator standard position error, it will store DTC C1593/53.

DTC No.DTC Detecting ConditionTrouble Area
C1593/53The steering control ECU detects a steering actuator standard position error.Steering actuator

Signal transmission between the steering control ECU and steering angle sensor is performed via serial communication.

If an error occurs between them in serial communication, the ECU will store DTC C1595/55.

DTC No.DTC Detecting ConditionTrouble Area
C1595/55The steering control ECU detects an error in serial communication between the ECU and steering angle sensor.Steering angle sensor Wire harness and connector Steering control ECU

Scheme 23

Scheme 23: WIRING DIAGRAM

Scheme 24

Scheme 24: PROCEDURE

Scheme 25

Scheme 25
  1. CHECK DTC (CAN COMMUNICATION SYSTEM) Check for DTCs in the CAN communication system. Refer to «DIAGNOSIS SYSTEM»(ref-382784-S35354466232011012800000) . Result Result Proceed to DTC is not output A DTC is output B B --> GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) A: Go to next step
  2. CHECK STEERING ANGLE SENSOR Check that a steering angle sensor with the specified part number is installed. Standard A steering angle sensor with the specified part number (89245-30070) is installed. NG --> REPLACE STEERING ANGLE SENSOR OK: Go to next step
  3. CHECK WIRE HARNESS Turn the engine switch off. Disconnect the connectors from the steering control ECU and the steering angle sensor. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition K70-10 (SS1-) - K19-7 (SS1-) Below 1 ohms K70-19 (SS1+) - K19-8 (SS1+) Below 1 ohms K70-19 (SS1+) - Body ground 10 kohms or higher K70-10 (SS1-) - Body ground 10 kohms or higher K70-19 (SS1+) - K70-10 (SS1-) 1 kohms or higher NG --> REPAIR OR REPLACE WIRE HARNESS OK: Go to next step
  4. CHECK STEERING ANGLE SENSOR Connect the connector to the steering angle sensor. Adjust the shift lever to neutral. Jack up the vehicle. Turn the engine switch on (IG). Check the signal waveform according to the condition in the table below. Voltage Tester connection Condition Specified condition K70-19 (SS1+) - K70-10 (SS1-) Engine switch on (IG), rotate steering wheel slowly Pulse generation (0 <----> 5 V) HINT: The output voltage should fluctuate up and down similarly to the diagram on the left when the wheel is turned slowly. NG --> REPLACE STEERING ANGLE SENSOR OK --> REPLACE STEERING CONTROL ECU

The steering control ECU receives signals from the power steering ECU via local CAN communication.

If the steering control ECU cannot receive signals from the power steering ECU correctly via local CAN communication, it will store DTC C1597/57.

DTC No.DTC Detecting ConditionTrouble Area
C1597/57The steering control ECU detects a reception error of signals from the power steering ECU via local CAN communication.CAN communication system (Local CAN) Power steering ECU Steering control ECU

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Scheme 26: WIRING DIAGRAM

Scheme 27

Scheme 27: PROCEDURE
  1. CHECK WIRE HARNESS Disconnect the connectors from the steering control ECU and the power steering ECU. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition A40-4 (CAN+) - A23-1 (CAN+) Below 1 ohms A40-9 (CAN-) - A23-8 (CAN-) Below 1 ohms A40-4 (CAN+) - A40-9 (CAN-) 10 kohms or higher NG --> REPAIR OR REPLACE WIRE HARNESS OK: Go to next step
  2. REPLACE POWER STEERING ECU Replace the power steering ECU. Connect the connectors to the steering control ECU and the power steering ECU. Check for DTCs in the steering control ECU. Refer to «DTC CHECK / CLEAR»(ref-382810-S16608627522011012800000) . OK DTC C1597/57 is not output. NG --> REPLACE STEERING CONTROL ECU OK --> END

The steering control ECU drives the actuator while the steering wheel is turned to set the gear ratio. It detects the current flowing into the actuator motor driving circuit.

If the steering control ECU detects excessive current, it will store this DTC C15A1/61, turn on the master warning light, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15A1/61Excessive current (exceeding the estimated amount) flows due to a malfunction in the motor drive circuit.Wire harness and connector Steering actuator Steering control ECU

Scheme 28

Scheme 28: WIRING DIAGRAM

The steering control ECU drives the actuator based on steering angle sensor signals and vehicle speed signals.

If the steering control ECU detects excessive current flowing into the steering actuator, or an internal malfunction, it will turn on the master warning light, store DTC C15A2/62, and stop VGRS operation.

If the steering control ECU detects a malfunction in the predriver circuit, it will turn the master warning light on, store DTC C15A6/62, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15A2/62The VGRS system detects a malfunction in the motor drive circuit.Wire harness and connector Power source circuit Steering actuator Steering control ECU
C15A6/62The actual motor current value greatly differs from the estimated value.Power source circuit Wire harness and connector Steering actuator Steering control ECU

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Scheme 29: WIRING DIAGRAM

The steering actuator drives the internal motor using the current output from the steering control ECU to change the relative angle between tire angle and steering wheel angle.

The rotation angle sensor in the steering actuator detects the motor rotation angle and outputs this information to the steering control ECU.

If the steering control ECU detects a malfunction in the rotation angle sensor circuit, it will store DTC C15A3/63.

DTC No.DTC Detecting ConditionTrouble Area
C15A3/63The steering control ECU detects a malfunction in the rotation angle sensor circuit.Wire harness and connector Steering actuator Steering control ECU

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Scheme 30: WIRING DIAGRAM

Scheme 31

Scheme 31: PROCEDURE

Scheme 32

Scheme 32
  1. CHECK WIRE HARNESS Turn the engine switch off. Disconnect the connectors from the steering control ECU and the steering actuator. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition K70-4 (S1) - K26-2 (S1+) Below 1 ohms K70-6 (RV) - K26-1 (RV+) Below 1 ohms K70-14 (S2) - K26-9 (S2+) Below 1 ohms K70-15 (RG) - K26-10 (RG+) Below 1 ohms K70-4 (S1) - K70-6 (RV) 10 kohms or higher K70-4 (S1) - K70-14 (S2) 10 kohms or higher K70-4 (S1) - K70-15 (RG) 10 kohms or higher K70-6 (RV) - K70-14 (S2) 10 kohms or higher K70-6 (RV) - K70-15 (RG) 10 kohms or higher K70-14 (S2) - K70-15 (RG) 10 kohms or higher K70-4 (S1) - Body ground 10 kohms or higher K70-6 (RV) - Body ground 10 kohms or higher K70-14 (S2) - Body ground 10 kohms or higher K70-15 (RG) - Body ground 10 kohms or higher NG --> REPAIR OR REPLACE WIRE HARNESS OK: Go to next step
  2. CHECK STEERING ACTUATOR Connect the connector to the steering actuator. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition K70-4 (S1) - K70-6 (RV) Below 100 ohms K70-4 (S1) - K70-14 (S2) Below 100 ohms K70-4 (S1) - K70-15 (RG) Below 100 ohms K70-6 (RV) - K70-14 (S2) Below 100 ohms K70-6 (RV) - K70-15 (RG) Below 100 ohms K70-14 (S2) - K70-15 (RG) Below 100 ohms K70-4 (S1) - Body ground 10 kohms or higher K70-6 (RV) - Body ground 10 kohms or higher K70-14 (S2) - Body ground 10 kohms or higher K70-15 (RG) - Body ground 10 kohms or higher NG --> REPLACE STEERING ACTUATOR OK --> REPLACE STEERING CONTROL ECU

When the VGRS system is normal, the steering actuator conducts current from the steering control ECU to the steering actuator solenoid to release the lock mechanism, enabling motor operation.

The steering actuator does not operate under either of the following conditions

  1. The engine is off.
  2. The motor in the actuator is locked by the lock mechanism to prevent rotation. (Fail-safe function)
  3. The system is being protected from overheating. (Fail-safe function)

If the steering control ECU detects a malfunction in the steering actuator lock mechanism or a motor rotation angle error, it will store these DTCs.

DTC No.DTC Detecting ConditionTrouble Area
C15A4/64The steering control ECU detects that the difference between the actuator target angle and the actuator position is approximately 30° or more for 1 second.Steering actuator
C15A9/66The steering control ECU detects that the lock pin is not aligned with the lock holder correctly.Steering actuator
C15AA//66The steering control ECU cannot operate because the actuator lock cannot be released.Steering actuator
C15AB/66The steering control ECU detects that the lock pin cannot be inserted into the lock holder.Steering actuator

If the steering control ECU detects a malfunction in the lock mechanism, it will turn the master warning light on, store the DTC C15A5/65, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15A5/65The steering control ECU detects that the LG terminal voltage is abnormal.Wire harness and connector Steering actuator Steering control ECU

Scheme 33

Scheme 33: PROCEDURE

Scheme 34

Scheme 34
  1. CHECK WIRE HARNESS Turn the engine switch off. Disconnect the connectors from the steering control ECU and the steering actuator. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition K70-3 (LV) - K26-7 (LV+) Below 1 ohms K70-12 (LG) - K26-16 (LG+) Below 1 ohms K70-3 (LV) - Body ground 10 kohms or higher K70-12 (LG) - Body ground 10 kohms or higher Turn the engine switch on (IG). Measure the voltage according to the value(s) in the table below. Voltage Tester connection Specified condition K70-3 (LV) - Body ground Below 1 V K70-12 (LG) - Body ground Below 1 V NG --> REPAIR OR REPLACE WIRE HARNESS OK: Go to next step
  2. CHECK STEERING ACTUATOR Turn the engine switch off. Connect the connector to the steering control ECU. Measure the resistance according to the value(s) in the table below. Resistance Tester connection Specified condition K26-7 (LV+) - K26-16 (LG+) 10 to 100 ohms K26-7 (LV+) - Body ground 10 kohms or higher K26-16 (LG+) - Body ground 10 kohms or higher NG --> REPLACE STEERING ACTUATOR OK --> REPLACE STEERING CONTROL ECU

If the steering control ECU detects an internal malfunction, it will turn the master warning light on, store these DTCs, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15B1/71The steering control ECU detects an internal malfunction.Steering control ECU
C15B2/72The steering control ECU detects an internal malfunction.Steering control ECU
C15B3/73The steering control ECU detects an internal temperature error.Steering control ECU

If the steering control ECU detects an internal malfunction, it will turn the master warning light on, store DTCs C15B4/71, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15B4/71The steering control ECU detects an internal malfunction.Steering control ECU

The steering control ECU detects a steering angle sensor malfunction by receiving an error signal from the steering angle sensor via CAN communication. If the steering control ECU detects this error signal, it will turn the master warning light on, store these DTCs, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15C1/74The steering control ECU receives a steering angle sensor malfunction signal via CAN communication.Steering angle sensor Steering angle sensor Steering control ECU
C15C2/74The steering control ECU receives a B+ open circuit signal from the steering angle sensor via CAN communication.Steering angle sensor Steering angle sensor Steering control ECU

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Scheme 35: WIRING DIAGRAM

The steering control ECU detects a vehicle speed error by receiving an error signal from the skid control ECU via CAN communication.

If the steering control ECU detects this error signal, it will turn the master warning light on, store this DTC, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15C3/75The steering control ECU receives a vehicle speed error signal via CAN communication.Skid control ECU CAN communication system Steering control ECU

The steering control ECU monitors IG power supply voltage.

If the steering control ECU detects a malfunction, it will turn on the master warning light, store DTC C15C6/77, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15C6/77The steering control ECU detects that the battery voltage is normal and the IG terminal voltage is less than 4 V for 6 seconds.ECU-IG LH fuse IG circuit Charging system Steering control ECU

Scheme 36

Scheme 36: WIRING DIAGRAM

The steering control ECU monitors PIG (motor power source voltage) and detects a malfunction in the power supply relay (located inside the steering control ECU).

If the steering control ECU detects a malfunction, it will turn on the master warning light, store these DTCs, and stop VGRS operation.

DTC No.DTC Detecting ConditionTrouble Area
C15C7/78The steering control ECU detects that the IG terminal voltage is between 9 and 16 V, and the PIG terminal voltage is less than 7 V or more than 18.5 V for 2.4 seconds.VGRS fuse Wire harness and connector Power source circuit Steering control ECU
C15C8/79The steering control ECU detects a malfunction in the power source relay or an open circuit.VGRS fuse Wire harness and connector Steering control ECU

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Scheme 37: WIRING DIAGRAM

The steering control ECU receives signals from the ECM (engine ECU) via CAN communication.

If the steering control ECU detects an error in reception, it will output this DTC.

DTC No.DTC Detecting ConditionTrouble Area
U0100/56The steering control ECU detects an error in reception (from ECM) in CAN communication.CAN communication system ECM

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Scheme 38: WIRING DIAGRAM

The steering control ECU receives signals from the skid control ECU via CAN communication.

If the steering control ECU detests an error in reception, it will output this DTC.

DTC No.DTC Detecting ConditionTrouble Area
U0122/56The steering control ECU detects an error in reception (from skid control ECU) in CAN communication.CAN communication system Skid control ECU

Scheme 39

Scheme 39: WIRING DIAGRAM

The steering control ECU receives signals from the yaw rate (deceleration) sensor via CAN communication.

If the steering control ECU detects an error in reception, it will output this DTC.

DTC No.DTC Detecting ConditionTrouble Area
U0123/56The steering control ECU detects an error in reception (from yaw rate (deceleration) sensor) in CAN communication.CAN communication system Yaw rate (deceleration) sensor

Scheme 40

Scheme 40: WIRING DIAGRAM

The steering control ECU receives signals from the steering angle sensor via CAN communication.

If the steering control ECU detects an error in reception, it will output this DTC.

DTC No.DTC Detecting ConditionTrouble Area
U0126/56The steering control ECU detects an error in reception (from steering angle sensor) in CAN communication.CAN communication system Steering angle sensor

Scheme 41

Scheme 41: WIRING DIAGRAM

The steering control ECU receives signals from the power steering ECU via CAN communication.

If the steering control ECU detects an error in reception, it will output this DTC.

DTC No.DTC Detecting ConditionTrouble Area
U0123/56The steering control ECU detects an error in reception (from power steering ECU) in CAN communication.CAN communication system Power steering ECU

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Scheme 42: WIRING DIAGRAM

If the steering control ECU detects that VGRS system has a malfunction, warning information is transmitted to the combination meter via CAN and BEAN.

The combination meter will turn the master warning light on based on this information.

Warning information is transmitted via the following route

  1. Steering control ECU --> (CAN) --> Power steering ECU --> (CAN) --> Gateway ECU --> (BEAN) --> Combination meter

Connecting terminals TC and CG of the DLC3 makes the master warning light blink and outputs DTCs.

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Scheme 43: WIRING DIAGRAM