Variable Gear Ration Steering System (Diagnostics - Introduction): Other Lexus GS III facelift

PRECAUTION

1. TROUBLESHOOTING PRECAUTIONS If the problem is caused by a poor connection of a terminal or poor installation of a part, reconnecting the terminal, or removing and reinstalling the part may solve the problem, or may temporarily return the system to normal. To specify the cause of the problem, check for DTCs or confirm vehicle operating conditions when the problem occurred and note them down before disconnecting connectors or removing parts. Be sure to check for DTCs in other systems as the problem may be caused by a malfunction in another system. DTCs may be stored in the EPS and/or electronically controlled brake systems due to VGRS system inspections. Check for DTCs in the EPS and electronically controlled brake systems and clear any output codes after inspecting the VGRS system. When the engine switch is turned on/off, system start-up/stop operation is performed. At this time, a small operating sound can be heard and the steering wheel slightly moves in a turning direction. If "Inval" is displayed for "Straight Angle Valid Flag" in the data list, the VGRS system does not operate. If the steering wheel is turned left and right with the engine switch off, a noise can be heard. However, this is not a malfunction.
2. HANDLING AND OPERATIONAL PRECAUTIONS Removal and installation of the steering control ECU, steering actuator, and each sensor must be performed with the engine switch off unless specified. If the steering control ECU, steering actuator, or a sensor is removed and installed, perform the test mode inspection, check for DTCs, and confirm that the normal system code is output. If the engine switch is turned on (IG) with the steering control ECU connector disconnected, DTCs may be stored in the EPS and/or electronically controlled brake systems. Check for DTCs in those systems and clear any output codes after completing repair.
3. PRECAUTIONS FOR REPLACEMENT OF STEERING SYSTEM PARTS If the steering control ECU or steering actuator is replaced, perform actuator angle neutral point calibration and initialization. The steering control ECU cannot be disassembled or repaired. If there is any problem with the steering control ECU, replace with a new one.
4. PRECAUTIONS FOR STEERING WHEEL OFF-CENTER NOTE: If the steering wheel is still off-center after completing steering angle sensor initialization. Refer to «INITIALIZATION»(ref-382810-S14733650782011012800000) , perform VGRS system calibration. Refer to «CALIBRATION»(ref-382810-S39353253692011012800000) . HINT: The steering wheel may become off-center under any of the following conditions. These conditions do not indicate a malfunction. The steering wheel is turned when the engine switch is off. The steering wheel is turned quickly. The steering wheel is turned to the left or right lock position. If the steering wheel is off-center, drive the vehicle at 35 km/h (22 mph) or more for 5 seconds or more, or turn the steering wheel to the left and right with the vehicle stopped or while driving at low speeds. This may center the steering wheel.
5. CONDITIONS UNDER WHICH VGRS SYSTEM DOES NOT OPERATE The VGRS system does not operate under any of the following conditions: Power supply voltage is low or too high. A fail-safe function is operating to protect the system from overheating. (System control is suspended to prevent the motor in the steering actuator and the steering control ECU from overheating. If the temperatures of the motor and ECU drop, the system will return to normal.) The vehicle is exposed to extremely low temperatures. (If the ambient temperature becomes approximately -30°C, system control will be suspended.) NOTE: If any of the above occurs, perform steering angle sensor initialization. Refer to «INITIALIZATION»(ref-382810-S14733650782011012800000) .

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HINT

*1: Warning information signals are transmitted via the following route

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

TERMINALS OF ECU

HINT

Inspect the connectors from the back side while they are connected.

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*1: w/ Active Stabilizer Suspension System

*2: w/o Active Stabilizer Suspension System

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1. DIAGNOSTIC SYSTEM Inspect the battery voltage. Standard 11 to 14 V HINT: If the voltage is below 11 V, recharge the battery before proceeding. Check the DLC3. The steering control ECU uses CAN and ISO 9141-2 as its communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format. Verify the conditions listed in the table below. Symbols (Terminals No.) Terminal description Condition Specified condition SIL (7) - SG (5) Bus "+" line During transmission Pulse generation CG (4) - Body ground Chassis ground Always Below 1 ohms SG (5) - Body ground Signal ground Always Below 1 ohms BAT (16) - Body ground Battery positive Always 11 to 14 V CANH (6) - CANL (14) HIGH-level CAN bus line Engine switch off 54 to 67 ohms CANH (6) - Battery positive HIGH-level CAN bus line Engine switch off 1 Mohms or higher CANH (6) - CG (4) HIGH-level CAN bus line Engine switch off 3 kohms or higher CANL (14) - Battery positive LOW-level CAN bus line Engine switch off 1 Mohms or higher CANL (14) - CG (4) LOW-level CAN bus line Engine switch off 3 kohms or higher HINT: If the display shows a communication error message when you connect the cable of the Techstream to the DLC3, turn the engine switch on (IG) and operate the Techstream, there is a problem on either the vehicle side or the Techstream side. If communication is normal when the Techstream is connected to another vehicle, inspect the DLC3 on the original vehicle. If communication is still not possible when the Techstream is connected to another vehicle, the problem is probably in the Techstream itself. Consult the Service Department listed in the Techstream's instruction manual. If the problem still occurs after the above inspection is performed, there may be a problem with the DLC3 connector.
2. FUNCTION OF WARNING LIGHT AND MESSAGE If a malfunction occurs during system operation, the master warning light (VGRS) on the combination meter assembly will come on and "CHECK VGRS" will be displayed on the multi-information display to inform the driver of the system malfunction.
3. DTCs Normal mode. DTCs are memorized in the steering control ECU and read by using the Techstream. Refer to «DTC CHECK / CLEAR»(ref-382810-S16608627522011012800000) . Test mode. By switching from normal mode to test mode, the steering angle sensor can be inspected. Refer to «CHECK MODE PROCEDURE»(ref-382810-S21879498702011012800000) . HINT: Whether the system is in diagnostic mode or test mode can be checked from the indication on the multi-information display. For details of the indication and how to check, refer to "DTC CHECK/CLEAR". Refer to «DTC CHECK / CLEAR»(ref-382810-S16608627522011012800000) .
4. CHECK MASTER WARNING LIGHT Turn the engine switch on (IG). Check that the master warning light (VGRS) comes on for 2 seconds. HINT: If the master warning light (VGRS) check result is not normal, proceed to troubleshooting of the warning light circuit. Trouble Area See procedure Master warning light circuit Refer to «Master Warning Light Malfunction»(ref-382815-S18577805092011012800000)

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1. DTC CHECK (USING TECHSTREAM) HINT: If the DTC check/clear is performed using the Techstream, 2-digit codes will also be displayed on the multi-information display. Check for DTCs. Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Check the DTCs. Enter the following menus: Chassis / VGRS / Trouble Codes. Confirm the details of the DTCs. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-382810-S29110751752011012800000) . Clear the DTCs. Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Clear the DTCs. Enter the following menus: Chassis / VGRS / Trouble Codes. According to the display on the Techstream, select the trouble code data display with the clear button.
2. DTC CHECK (USING SST CHECK WIRE) HINT: The master warning light comes on in diagnostic mode. Check for DTCs. Using SST check wire, connect terminals TC and CG of the DLC3. SST: 09843-18040 Turn the engine switch on (IG). "DIAG VGRS" is displayed on the multi-information display and the system starts searching for a malfunction. If the system is normal, "DIAG VGRS OK" is displayed. If the system has a malfunction, "DIAG VGRS xx" is displayed. ("xx" is a 2-digit DTC.) Clear the DTCs. Turn the engine switch on (IG). Using SST check wire, connect and disconnect terminals TC and CG of the DLC3 4 times within 8 seconds. SST: 09843-18040 Disconnect SST check wire from the DLC3. NOTE: The stored yaw rate sensor value will be cleared by the above operation. Obtain the yaw rate sensor zero point. Turn the engine switch off. HINT: If the problem still exists, DTCs may not be cleared. Refer to «CALIBRATION»(ref-382793-S40522261552011012800000) . Obtain the yaw rate sensor zero point.

FREEZE FRAME DATA

HINT

The VGRS system stores data when a trouble code is set and can be viewed using the Techstream.

1. FREEZE FRAME DATA OF STEERING CONTROL ECU Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Check the freeze frame data. Enter the following menus: Chassis / VGRS / Utility / Freeze Frame Data. VGRS Tester Display Measurement Item Value (Unit) Vehicle Speed (Vsc ECU) Vehicle speed (VSC ECU) Speed indicated on speedometer (km/h) Engine Revolution (Rpm) Engine revolution (rpm) Less than 300 or more then 300 (rpm) Mtr Power Source Cur. Motor power source actual current 0 to 127.5 (A) PIG-Power Source Volt PIG power source voltage 0 to 25.5 (V) IG-Power Source Volt IG power source voltage 0 to 25.5 (V) Lock Motor Output Volt LOCK motor output voltage 0 to 25.5 (V) Command Value Duty Command value DUTY for PVM control 0 to 100 (%) Actuator Lock Duty Val Command value DUTY for actuator lock control 0 to 100 (%) Resolver Offset (SIN) Resolver offset (SIN) 0 to 25.5 (V) Resolver Offset (COS) Resolver offset (COS) 0 to 25.5 (V) Motor Current U Motor current U -63 to 64.5 (A) Motor Current V Motor current V -63 to 64.5 (A) Motor Current W Motor current W -63 to 64.5 (A) Motor Voltage Motor power supply voltage 0 to 51 (V) Steering Pos1 Steering position1 -2047 to 2048.9375 (deg) Actuator Position Actuator position -2047 to 2048.9375 (deg) Steering Angle Velocity Steering wheel angle velocity -2047 to 2048.9375 (deg/s) Actuator Target Angle1 Actuator target angle1 -2047 to 2048.9375 (deg) Actuator Target Angle2 Actuator target angle2 -2047 to 2048.9375 (deg) Actuator Revolution Spd Actuator revolution speed -2047 to 2048.9375 (deg) Mode State Mode state 00 to 04, 06 to 10, 0A, 0B, 0C, 0D, 0E, and 0F

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1. TEST MODE (VGRS SENSOR SIGNAL CHECK) HINT: When the system enters test mode, "VGRS TEST MODE" is displayed on the multi-information display. Before entering test mode, check and repair any malfunctions indicated by the present DTCs of the VGRS system. By switching from normal mode to test mode, the steering angle sensor can be read. When entering test mode, the steering control ECU sets all the test mode DTCs first. When the mode is switched from test mode to normal mode, all the test mode DTCs will be erased. Check the test mode DTCs (using the Techstream). Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Read the test mode DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream's operator's manual for further details. Clear the test mode DTCs (using the Techstream). Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Switch the system from test mode to normal mode by following the directions on the Techstream screen. HINT: Refer to the Techstream's operator's manual for further details. Check the test mode DTCs (using SST check wire). Turn the engine switch off. Using SST check wire, connect terminals TS (TC) and CG of the DLC3. SST: 09843-18040 Turn the engine switch on (IG). Read 2-digit test mode DTCs from the multi-information display. NOTE: Perform these procedures with the vehicle stopped. Clear the test mode DTCs (using SST check wire). Turn the engine switch off. Disconnect the SST check wire from the DLC3. SST: 09843-18040 Turn the engine switch on (IG). HINT: If the engine switch is turned on (IG) with terminals TS and CG short-circuited, the system remains in test mode.
2. TEST MODE DTC If a trouble code is displayed during the DTC check, check the circuit indicated by the DTC. For details of each code, proceed to DTC chart. DTC No. Detection Item Trouble Area C15C4/74 A steering signal indicating a tire angle of 36°or more (to the left or right) is input after transfer to test mode. (*1) Steering angle sensor Steering control ECU C15C5/75 A steering signal indicating a motor rotation angle of 36°or more (to the left or right) is input after transfer to test mode. (*1) Steering angle sensor Steering control ECU HINT: *1: A tire angle of 36° and a motor rotation angle of 36° correspond to the steering wheel angle respectively. The amount of change in tire angle and motor rotation angle is from when the mode is changed to test mode.