Electronic Power Steering System (Diagnostics - Introduction): Diagnosis Lexus GS III рестайлинг

HOW TO PROCEED WITH TROUBLESHOOTING

Perform troubleshooting according to the following flowchart.

HINT

1. For further details, see appropriate service information given.
2. *: Use the Techstream.

1. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step
2. CHECK DTC AND FREEZE FRAME DATA* Record DTCs and freeze frame data. NEXT: Go to next step
3. CLEAR DTC AND FREEZE FRAME DATA* NEXT: Go to next step
4. PROBLEM SYMPTOM CONFIRMATION Result Result Proceed to Symptom does not occur A Symptom occur B B --> GO TO STEP 6 A: Go to next step
5. SYMPTOM SIMULATION NEXT: Go to next step
6. CHECK DTC* Check for DTC. Delete the DTC. Recheck for DTC. Result Result Proceed to DTC does not reoccur A DTC reoccurs B HINT: Refer to the diagnostic trouble code chart if any DTCs are output. If any CAN communication system DTCs are output, perform troubleshooting on the CAN communication system first. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING»(ref-387091-S07682503522011022400000) . If communication to the power steering ECU assembly is not established through the Techstream, inspect terminals SIL of the DLC3 and power steering ECU assembly, and inspect the IG circuit of the power steering ECU. B --> GO TO STEP 8 A: Go to next step
7. PROBLEM SYMPTOMS TABLE NEXT: Go to next step
8. DTC CHART NEXT: Go to next step
9. CIRCUIT INSPECTION NEXT: Go to next step
10. IDENTIFICATION OF PROBLEM NEXT: Go to next step
11. REPAIR OR REPLACE NEXT: Go to next step
12. CONFIRMATION TEST NEXT --> END

PROBLEM SYMPTOMS TABLE

HINT

Use the table below to help determine the cause of the problem symptom. The potential causes of the symptoms are listed in order of probability in the "Suspected area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.

ELECTRONIC POWER STEERING SYSTEM

Scheme 21

Scheme 22

1. TERMINALS OF ECU HINT: The power steering ECU has waterproof connectors. Therefore, voltage or waveforms cannot be checked with the connectors connected to the vehicle. Symbols (Terminal No. ) Wiring Color Terminal Description CAN+ (A23-1) W Local CAN communication CANH (A23-2) W High-level CAN bus line CANL (A23-3) B Low-level CAN bus line PIG (A23-4) W Power source PGND (A23-5) B Power ground CAN- (A23-8) B Local CAN communication IG (A23-9) B-Y IG power source SIL (A23-10) R Diagnosis communication signal RLY (A23-11) LG-B EPS relay drive signal TRQV (C4-1) W Torque sensor power source RZV (C4-2) B Rotation angle sensor power source RZCS (C4-3) R COS phase input signal (Rotation angle sensor) RZSN (C4-4) W SIN phase input signal (Rotation angle sensor) U (C4-5) B U phase motor output W (C4-6) R W phase motor output INSN (C4-7) G-W SIN phase input signal (torque sensor input shaft side) INCS (C4-8) R-L COS phase input signal (torque sensor input shaft side) OUSN (C4-9) G-B SIN phase input signal (torque sensor output shaft side) OUCS (C4-10) Y-B COS phase input signal (torque sensor output shaft side) V (C4-11) W V phase motor output TQG1 (C4-12) L-W Torque sensor power source circuit ground RZG (C4-13) G Rotation angle sensor power source circuit ground TQG2 (C4-14) R-B Torque sensor detection circuit ground SRZG (C4-15) BR Rotation angle sensor shield ground
2. CHECK WIRE HARNESS SIDE CONNECTOR Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition PIG (A23-4) - PGND (A23-5) W-B Power source Always Below 1 V PGND (A23-5) - Body ground B - Body ground Power ground Always Below 1 ohms IG (A23-9) - PGND (A23-5) B-Y - B IG power source Power switch ON (IG) 10 to 14 V RLY (A23-11) - PGND (A23-5) LG-B - B EPS relay drive signal Always 10 to 14 V U (C4-5) - W (C4-6)/ V (C4-11) B - R/W U phase motor output Always Below 1 ohms W (C4-6) - U (C4-5)/ V (C4-11) R - B/W W phase motor output Always Below 1 ohms V (C4-11) - U (C4-5)/ W (C4-6) W - B/R V phase motor output Always Below 1 ohms

Scheme 23

1. DESCRIPTION Connecting the Techstream to the vehicle and reading various data output from the power steering ECU is the only difference between usual troubleshooting procedures and those for a vehicle with a diagnostic system. The power steering ECU records DTCs when the ECU detects a malfunction in the ECU itself or in its circuits. To check the DTCs, connect the Techstream to the DLC3. The Techstream enables you to erase the DTCs and check the freeze frame data and various forms of steering data.
2. CHECK DLC3 If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector. HINT: The vehicle uses ISO 15765-4 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format. Symbols (Terminal No.) Terminal Description Condition Specified Condition SIL (7) - SG (5) Bus "+" line During communication 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) CAN bus line Power switch OFF* 54 to 67 ohms CANH (6) - BAT (16) HIGH-level CAN bus line Power switch OFF* 6 kohms or higher CANH (6) - CG (4) HIGH-level CAN bus line Power switch OFF* 200 ohms or higher CANL (14) - BAT (16) LOW-level CAN bus line Power switch OFF* 6 kohms or higher CANL (14) - CG (4) LOW-level CAN bus line Power switch OFF* 200 ohms or higher NOTE: *: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector. HINT: Connect the Techstream cable to the DLC3, turn the power switch ON (IG), and attempt to use the Techstream. If the screen displays a communication error message, a problem exists on the vehicle side or the Techstream side. If communication is normal when connecting the Techstream to another vehicle, inspect the DLC3 on the original vehicle. If communication is still not possible when connecting the Techstream to another vehicle, the problem is probably in the Techstream itself. Consult the Service Department listed in the Techstream's operator's manual.
3. P/S WARNING LIGHT If a problem occurs in the power steering system, the P/S warning light will come on in the combination meter.

DTC CHECK / CLEAR

1. CHECK DTC Connect the Techstream to the DLC3. Turn the power switch ON (IG). Turn the Techstream on. Read the DTCs by following the display on the Techstream. Enter the following menus: Chassis / EMPS / Trouble Codes.
2. CLEAR DTC Connect the Techstream to the DLC3. Turn the power switch ON (IG). Turn the Techstream on. Clear the DTCs by following the display on the Techstream. Enter the following menus: Chassis / EMPS / Trouble Codes.

DATA LIST / ACTIVE TEST

1. DATA LIST HINT: Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection an be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time. NOTE: In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not. Connect the Techstream to the DLC3. Turn the power switch ON (IG). Operate the Techstream according to the steps on the display and select Data List. Enter the following menus: Chassis / EMPS / Data List. EMPS Tester Display Measurement Item/Range Normal Condition Diagnostic Note Torque Sensor 1 Output Torque sensor 1 rotation angle/ Min.: 0 deg, Max.: 360 deg Value changes from 0 to 360° every 22.5° of steering angle Steering wheel is turned Torque Sensor 2 Output Torque sensor 2 rotation angle/ Min.: 0 deg, Max.: 360 deg Value changes from 0 to 360° every 22.5° of steering angle Steering wheel is turned Meter Vehicle Velocity Vehicle speed from meter/ Min.: 0 km/h (0 mph), Max.: 255 km/h (158 mph) 0 km/h (0 mph) Vehicle is stopped No significant fluctuation Vehicle is driven at a constant speed Engine Revolution Engine revolution/ Min.: 0 RPM, Max.: 8192 RPM No significant fluctuation Engine is running at a constant speed Motor Actual Current Amount of current to motor/ Min.: -128 A, Max.: 127 A Value changes in proportion to steering effort Power steering is in operation Command Value Current Demanded amount of current to motor/ Min.: -128 A, Max.: 127 A Value changes in proportion to steering effort Power steering is in operation Steering Angle Velocity Steering angle speed/Min.: -4096 deg/sec, Max.: 4064 deg/sec Value changes in proportion to steering speed Steering wheel is turned Thermistor Temperature ECU substrate temperature/ Min.: -50°C, Max.: 205°C - Power switch ON (IG) PIG Power Supply Power source voltage to activate motor/ Min.: 0 V, Max.: 25.5 V 10 to 14 V Power steering is in operation IG Power Supply ECU power source voltage/ Min.: 0 V, Max.: 25.5 V 10 to 14 V Power switch ON (IG) TRQ1 Zero Point Value Zero point value of torque sensor 1/ Min.: 0 deg, Max.: 360 deg Values differ depending on vehicle Steering wheel is not turned (without load) TRQ2 Zero Point Value Zero point value of torque sensor 2/ Min.: 0 deg, Max.: 360 deg Values differ depending on vehicle Steering wheel is not turned (without load) Steering Wheel Torque Steering torque/ Min.: -7.0 N*m, Max.: 7.0 N*m Value changes in proportion to steering effort Steering wheel is turned Motor Rotation Angle Motor rotation angle/ Min.: 0 deg, Max.: 360 deg Value changes from 0 to 360° every 22.5° of steering angle Steering wheel is turned Command Val Current 2 Amount of current demanded by motor 2/ Min.: -128 A, Max.: 127 A Value changes in proportion to steering effort Power steering is in operation PIG2 Voltage Coil rear pressurization voltage/ Min.: 0 V, Max.: 64 V 10 to 15 V Power steering is in operation Motor Voltage Motor power source voltage/ Min.: 0 V, Max.: 64 V 27 to 34 V Power steering is in operation Motor Terminal Volt (U) Motor terminal voltage (U phase)/ Min.: 0 V, Max.: 64 V 12 to 15 V Steering wheel is not turned 2 to 34 V Steering wheel is turned Motor Terminal Volt (V) Motor terminal voltage (V phase)/ Min.: 0 V, Max.: 64 V 12 to 15 V Steering wheel is not turned 2 to 34 V Steering wheel is turned Motor Terminal Volt (W) Motor terminal voltage (W phase)/ Min.: 0 V, Max.: 64 V 12 to 15 V Steering wheel is not turned 2 to 34 V Steering wheel is turned Steering Angle Sens Sig Steering angle sensor signal state/ OK or NG (1) or NG (2) or NG (3) Steering angle sensor signal is received OK The learning has not completed NG (1) Steering sensor abnormal NG (2) Communication error NG (3) Motor Overheat Record Continuous overheat prevention control record/ Unrec or Rec - - Motor Lo Power Record PIG power source voltage drop record/ Unrec or Rec - - Engine Rev Inter Record Record of engine revolution signal interruption/ Unrec or Rec - - Str Angle Inter Record Record of steering angle sensor signal interruption/ Unrec or Rec - - Spd Sig Invalid Record Record of vehicle speed signal invalid/ Unrec or Rec - - Battery Voltage Lo Record Battery voltage drop record/ Min.: 0 time, Max.: 255 times 0 to 255 times - Control Mode Codes indicating DTC detection timing during ECU control are displayed in hexadecimal/ Min.: 0, Max.: 255 0 to 255 This value indicated the ECU control mode when the DTC was detected. IG ON/OFF Times Number of times IG switch is turned on after DTC detection/ Min.: 0 times, Max.: 255 times 0 to 255 times - The Number of DTCs Number of detected DTCs when freeze frame data is stored/ Min.: 0, Max.: 255 - - ECU Identification ECU identification information/ 01 to 09, 11 or 12 - - Test Mode Status Selected mode/ Normal or Test

DIAGNOSTIC TROUBLE CODE CHART

HINT

If a trouble code is displayed during the DTC check, check the trouble area listed for that code in the table below. Then proceed to the "See" below.

ELECTRONIC POWER STEERING SYSTEM