LIN Communication System (Diagnostics - Introduction): Diagnosis Lexus GS IV

HOW TO PROCEED WITH TROUBLESHOOTING [03/2012 - ]

HINT

1. Use these procedures to troubleshoot the LIN communication system.
2. *: Use the Techstream.

1. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step
2. INSPECT AUXILIARY BATTERY VOLTAGE Standard voltage 11 to 14 V If the voltage is below 11 V, recharge or replace the auxiliary battery before proceeding. NEXT: Go to next step
3. CHECK COMMUNICATION FUNCTION OF CAN COMMUNICATION SYSTEM* Using the Techstream, inspect the CAN communication function to ensure there are no malfunctions in the communication system. Refer to «DIAGNOSTIC TROUBLE CODE CHART [03/2012 - ]»(ref-600620-S30655672282014022400000) . RESULT Result Proceed to No DTCs output A DTCs output B B --> GO TO CAN COMMUNICATION SYSTEM. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING [03/2012 - ]»(ref-600588-S38298476802014022400000) A: Go to next step
4. CHECK COMMUNICATION FUNCTION OF LIN COMMUNICATION SYSTEM* Using the Techstream, inspect the LIN communication function to ensure there are no malfunctions in the communication system. RESULT Result Proceed to No DTCs output A DTCs output B B --> DIAGNOSTIC TROUBLE CODE CHART. Refer to «DIAGNOSTIC TROUBLE CODE CHART [03/2012 - ]»(ref-600622-S25800085042014022400000) A: Go to next step
5. PROBLEM SYMPTOMS TABLE Refer to Problem Symptoms Table. Refer to «PROBLEM SYMPTOMS TABLE [03/2012 - ]»(ref-600622-S20622106862014022400000) . RESULT Result Proceed to Fault is not listed in problem symptoms table A Fault is listed in problem symptoms table B B --> ADJUST, REPAIR OR REPLACE N ACCORDANCE WITH PROBLEM SYMPTOMS TABLE A: Go to next step
6. OVERALL ANALYSIS AND TROUBLESHOOTING* Data List/Active Test. Refer to «DATA LIST / ACTIVE TEST [03/2012 - ]»(ref-600622-S26879136282014022400000) Terminals of ECU. Refer to «TERMINALS OF ECU [03/2012 - ]»(ref-600622-S42311105062014022400000) NEXT: Go to next step
7. ADJUST, REPAIR OR REPLACE NEXT --> END

PROBLEM SYMPTOMS TABLE [03/2012 - ]

HINT

1. Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, 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.
2. Inspect the fuses and relays related to this system before inspecting the suspected areas below.

LIN COMMUNICATION SYSTEM

1. *: w/ Rain Sensor

Scheme 166

Scheme 167

Scheme 168

Scheme 169

Scheme 170

Scheme 171

Scheme 172

Scheme 173

Scheme 174

Scheme 175

Scheme 176

Scheme 177

Scheme 178

Scheme 179

Scheme 180

Scheme 181

Scheme 182

Scheme 183

1. CHECK COWL SIDE JUNCTION BLOCK LH, MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) TEXT IN ILLUSTRATION *1 Main body ECU (Multiplex Network Body ECU) - - Remove the main body ECU (multiplex network body ECU) from the cowl side junction block LH. Refer to «REMOVAL [03/2012 - ]»(ref-600595-S12145438012014022400000) . Reconnect the cowl side junction block LH connectors. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition A-32 (IG) - Body ground - IG power supply Power switch on (IG) 11 to 14 V A-30 (BECU) - Body ground - Battery power supply Always 11 to 14 V A-29 (ACC) - Body ground - ACC power supply Power switch on (ACC) 11 to 14 V A-11 (GND1) - Body ground - Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
2. CHECK POWER MANAGEMENT CONTROL ECU Disconnect the N91 and N92 power management control ECU connectors. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N91-1 (AM22) - N91-6 (E1) P - W-B Constant power source Power switch on (IG) 11 to 14 V N92-7 (AM21) - N91-6 (E1) P - W-B Constant power source Power switch on (IG) 11 to 14 V N91-6 (E1) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
3. CHECK FRONT MULTIPLEX NETWORK DOOR ECU LH Disconnect the Q19 front multiplex network door ECU LH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Q19-3 (SIG) - Body ground B - Body ground IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V Q19-4 (CPUB) - Body ground P - Body ground Battery power supply Always 11 to 14 V Q19-6 (BDR) - Body ground V - Body ground Battery power supply Always 11 to 14 V Q19-16 (BCUT) - Body ground W - Body ground Battery power supply Always 11 to 14 V Q19-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
4. CHECK FRONT MULTIPLEX NETWORK DOOR ECU RH Disconnect the Q4 front multiplex network door ECU RH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Q4-3 (SIG) - Body ground B - Body ground IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V Q4-4 (CPUB) - Body ground P - Body ground Battery power supply Always 11 to 14 V Q4-6 (BDR) - Body ground V - Body ground Battery power supply Always 11 to 14 V Q4-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
5. CHECK MULTIPLEX NETWORK MASTER SWITCH ASSEMBLY Disconnect the Q25 multiplex network master switch assembly connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Q25-12 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms Q25-11 (B) - Q25-12 (GND) P - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
6. CHECK FRONT POWER WINDOW REGULATOR MOTOR ASSEMBLY LH Disconnect the Q17 front power window regulator motor assembly LH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Q17-1 (E) - Body ground BR - Body ground Ground Always Below 1 ohms Q17-2 (B) - Q17-1 (E) R - BR Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
7. CHECK FRONT POWER WINDOW REGULATOR MOTOR ASSEMBLY RH Disconnect the Q2 front power window regulator motor assembly RH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Q2-1 (E) - Body ground BR - Body ground Ground Always Below 1 ohms Q2-2 (B) - Q2-1 (E) R - BR Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
8. CHECK REAR POWER WINDOW REGULATOR MOTOR ASSEMBLY LH Disconnect the R9 rear power window regulator motor assembly LH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition R9-1 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms R9-2 (B) - R9-1 (E) R - W-B Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
9. CHECK REAR POWER WINDOW REGULATOR MOTOR ASSEMBLY RH Disconnect the R1 rear power window regulator motor assembly RH connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition R1-1 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms R1-2 (B) - R1-1 (E) R - W-B Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
10. CHECK SLIDING ROOF DRIVE GEAR SUB-ASSEMBLY (w/ Sliding Roof System) Disconnect the Y4 sliding roof drive gear sub-assembly connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Y4-12 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms Y4-8 (B) - Y4-12 (E) L - W-B Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
11. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Disconnect the N94 and N95 certification ECU connectors. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N94-1 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms N95-5 (+B) - N94-1 (E) GR - W-B Battery power supply Always 11 to 14 V N95-16 (IG) -N94-1 (E) B - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
12. CHECK ID CODE BOX (IMMOBILIZER CODE ECU) Disconnect the N73 ID code box connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N73-5 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms N73-1 (+B) - N73-5 (GND) GR - W-B Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
13. CHECK STEERING LOCK ACTUATOR ASSEMBLY Disconnect the N24 steering lock actuator assembly connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N24-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms N24-7 (B) - N24-1 (GND) L - W-B Battery power supply Always 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
14. CHECK RAIN SENSOR (w/ Rain Sensor) Disconnect the Y5 rain sensor connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Y5-2 (ES) - Body ground W - Body ground Ground Always Below 1 ohms Y5-4 (SIG) - Y5-2 (ES) P - W IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
15. CHECK REFRESHING SEAT SWITCH (w/ Seat Heater System) Disconnect the N72 refreshing seat switch connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N72-4 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms N72-1 (IG) - N72-4 (E) LG - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.
16. CHECK REAR CONTROL SWITCH (w/ Rear Control Switch) Disconnect the Z1 rear control switch connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition Z1-7 (IG+) - Z1-5 (E) L - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V Z1-5 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
17. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY Disconnect the N78 air conditioning amplifier assembly connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N78-5 (IG+) - N78-1 (GND) L - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V N78-6 (+B1) - N78-1 (GND) W - W-B Battery power supply Always 11 to 14 V N78-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
18. CHECK WINDSHIELD WIPER SWITCH ASSEMBLY Disconnect the N35 windshield wiper switch assembly connector. Measure the resistance and voltage according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition N35-7 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms N35-2 (+B) - N35-7 (E) SB - W-B IG power supply Power switch off --> Power switch on (IG) Below 1 V --> 11 to 14 V If the result is not as specified, there may be a malfunction on the wire harness side.

DTC CHECK / CLEAR [03/2012 - ]

HINT

Refer to the Techstream operator's manual for further details.

1. CHECK DTC Connect the Techstream to the DLC3. Turn the power switch on (IG) and turn the Techstream on. Enter the following menus: Body Electrical / (desired system) / Trouble Codes. Read the DTCs by following the directions on the screen.
2. CLEAR DTC Connect the Techstream to the DLC3. Turn the power switch on (IG) and turn the Techstream on. Enter the following menus: Body Electrical / (desired system) / Trouble Codes. Erase the DTCs by following the directions on the screen.

DATA LIST / ACTIVE TEST [03/2012 - ]

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 can 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 to on (IG). Turn the Techstream on. Enter the following menus: Body Electrical / Main Body / Data List / All Data. According to the display on the Techstream, read the Data List. MAIN BODY Tester Display Measurement Item/Range Normal Condition Diagnostic Note Communication D-Door Motor Connection status between front power window regulator motor assembly LH and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection When there is a malfunction, a DTC is stored. Communication P-Door Motor Connection status between front power window regulator motor assembly RH and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection When there is a malfunction, a DTC is stored. Communication RR-Door Motor Connection status between rear power window regulator motor assembly RH and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection When there is a malfunction, a DTC is stored. Communication RL-Door Motor Connection status between rear power window regulator motor assembly LH and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection When there is a malfunction, a DTC is stored. Communication Slide Roof Connection status between sliding roof drive gear sub-assembly and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection w/ Sliding Roof System When there is a malfunction, a DTC is stored. w/o Sliding Roof System "STOP" is always displayed as there is no connection to the LIN communication system. Communication Master SW Connection status between multiplex network master switch assembly and main body ECU (multiplex network body ECU) / OK or STOP OK: Connection STOP: No connection When there is a malfunction, a DTC is stored. The Number of DTC Number of trouble codes / Min.: 0, Max.: 255 Number of stored DTCs - NOTE: When the Techstream display is changed to "All Data", items that are not applicable to the vehicle may be displayed.

DIAGNOSTIC TROUBLE CODE CHART [03/2012 - ]

HINT

If a trouble code is output during the DTC check, inspect the trouble areas listed for that code. For details of the code, refer to the "See" below.

LIN COMMUNICATION SYSTEM

1. *1: w/ Sliding Roof System
2. *2: w/ Rear Control Switch
3. *3: w/ Seat Heater System