LIN Communication System (Diagnostics - Introduction): Diagnosis Lexus CT I

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

1. Use the following procedure to troubleshoot the LIN communication system.

1. *: Use the Techstream.

1. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step
2. CUSTOMER PROBLEM ANALYSIS In troubleshooting, confirm that the problem symptoms have been accurately identified. Preconceptions should be discarded in order to make an accurate judgment. To clearly understand what the problem symptoms are, it is extremely important to ask the customer about the problem and the conditions at the time the malfunction occurred. Gather as much information as possible for reference. Past problems that seem unrelated may also help in some cases. The following 5 items are important points in problem analysis: What Vehicle model, system name When Date, time, occurrence frequency Where Road conditions Under what conditions? Driving conditions, weather conditions How did it happen? Problem symptoms NEXT: Go to next step
3. INSPECT AUXILIARY BATTERY VOLTAGE Measure the auxiliary battery voltage with the power switch off. Standard Voltage 11 to 14 V If the voltage is below 11 V, recharge or replace the auxiliary battery before proceeding to the next step. NEXT: 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. Refer to «DTC CHECK / CLEAR»(ref-568820-S20386481962013072300000) . Result Result Proceed to DTC is not output A DTC is output B B --> GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-568820-S18233360872013072300000) A: Go to next step
5. PROBLEM SYMPTOMS TABLE Refer to Problem Symptoms Table. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568820-S32625048352013072300000) . Result Result Proceed to Fault is not listed in Problem Symptoms Table A Fault is listed in Problem Symptoms Table B B --> Go to step 7 A: Go to next step
6. OVERALL ANALYSIS AND TROUBLESHOOTING* Terminals of ECU. Refer to «TERMINALS OF ECU»(ref-568820-S30825895452013072300000) Data List / Active Test. Refer to «DATA LIST / ACTIVE TEST»(ref-568820-S00512526522013072300000) NEXT: Go to next step
7. REPAIR OR REPLACE NEXT: Go to next step
8. CONFIRMATION TEST NEXT --> END

PROBLEM SYMPTOMS TABLE

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

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1. CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Disconnect the 2C and 2B instrument panel junction block assembly connectors. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connectors disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition 2C-18 (BECU) - Body ground B - Body ground Auxiliary battery power supply Power switch off 11 to 14 V 2B-6 (GND1) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the 2C and 2B instrument panel junction block assembly connectors. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition 2D-26 (LIN2) - 2B-6 (GND1) P - W-B LIN communication line Power switch on (IG) Pulse generation 2A-27 (LIN2) - 2B-6 (GND1) P - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the main body ECU (multiplex network body ECU) or instrument panel junction block assembly may be malfunctioning.
2. CHECK POWER WINDOW REGULATOR MOTOR ASSEMBLY (for Driver Side) Disconnect the K2 power window regulator motor assembly (for driver side) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition K2-2 (B) - K2-1 (GND) L - W-B Auxiliary battery power supply Power switch off 11 to 14 V K2-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the K2 power window regulator motor assembly (for driver side) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition K2-9 (LIN) - K2-1 (GND) B - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the power window regulator motor assembly (for driver side) may be malfunctioning.
3. CHECK POWER WINDOW REGULATOR MOTOR ASSEMBLY (for Front Passenger Side) Disconnect the J2 power window regulator motor assembly (for front passenger side) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition J2-2 (B) - J2-1 (GND) L - W-B Auxiliary battery power supply Power switch off 11 to 14 V J2-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the J2 power window regulator motor assembly (for front passenger side) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition J2-9 (LIN) - J2-1 (GND) P - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the power window regulator motor assembly (for front passenger side) may be malfunctioning.
4. CHECK POWER WINDOW REGULATOR MOTOR ASSEMBLY (for Rear RH Side) Disconnect the L2 power window regulator motor assembly (for rear RH side) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition L2-2 (B) - L2-1 (GND) R - W-B Auxiliary battery power supply Power switch off 11 to 14 V L2-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the L2 power window regulator motor assembly (for rear RH side) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition L2-9 (LIN) - L2-1 (GND) P - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the power window regulator motor assembly (for rear RH side) may be malfunctioning.
5. CHECK POWER WINDOW REGULATOR MOTOR ASSEMBLY (for Rear LH Side) Disconnect the M2 power window regulator motor assembly (for rear LH side) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition M2-2 (B) - M2-1 (GND) R - W-B Auxiliary battery power supply Power switch off 11 to 14 V M2-1 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the M2 power window regulator motor assembly (for rear LH side) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition M2-9 (LIN) - M2-1 (GND) P - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the power window regulator motor assembly (for rear LH side) may be malfunctioning.
6. CHECK MULTIPLEX NETWORK MASTER SWITCH ASSEMBLY Disconnect the K5 multiplex network master switch assembly connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition K5-11 (B) - K5-12 (GND) L - W-B Auxiliary battery power supply Power switch off 11 to 14 V K5-12 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the K5 multiplex network master switch assembly connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition K5-17 (LIN1) - K5-12 (GND) P - W-B LIN communication line Power switch on (IG) Pulse generation K5-16 (LIN2) - K5-12 (GND) B - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the multiplex network master switch assembly may be malfunctioning.
7. CHECK SLIDING ROOF ECU (SLIDING ROOF DRIVE GEAR ASSEMBLY) (w/ Sliding Roof System) Disconnect the T10 sliding roof ECU (sliding roof drive gear assembly) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition T10-1 (B) - T10-2 (E) R - W-B Auxiliary battery power supply Power switch off 11 to 14 V T10-2 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the T10 sliding roof ECU (sliding roof drive gear assembly) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition T10-4 (LIN) - T10-2 (E) P - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the sliding roof ECU (sliding roof drive gear assembly) may be malfunctioning.
8. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Disconnect the H1 certification ECU (smart key ECU assembly) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition H1-1 (+B) - H1-15 (E) B - W-B Auxiliary battery power supply Power switch off 11 to 14 V H1-15 (E) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the H1 certification ECU (smart key ECU assembly) connector. Measure the voltage and check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition H1-16 (IG) - H1-15 (E) BE - W-B Power switch power supply Power switch on (IG) 11 to 14 V H1-16 (IG) - H1-15 (E) BE - W-B Power switch power supply Power switch off Below 1 V H1-29 (LIN) - H1-15 (E) B - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the certification ECU (smart key ECU assembly) may be malfunctioning.
9. CHECK ID CODE BOX (IMMOBILIZER CODE ECU) Disconnect the H22 ID code box (immobilizer code ECU) connector. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connector disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition H22-1 (+B) - H22-8 (GND) L - W-B Auxiliary battery power supply Power switch off 11 to 14 V H22-8 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the H22 ID code box (immobilizer code ECU) connector. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition H22-3 (LIN1) - H22-8 (GND) B - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the ID code box (immobilizer code ECU) may be malfunctioning.
10. CHECK TRANSMISSION CONTROL ECU ASSEMBLY Disconnect the A21 and A22 transmission control ECU assembly connectors. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connectors disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition A21-15 (BATT) - Body ground SB - Body ground Auxiliary battery power supply Power switch off 11 to 14 V A22-1 (E1) - Body ground BR - Body ground Ground Always Below 1 ohms A22-5 (E02) - Body ground W-B - Body ground Ground Always Below 1 ohms A22-6 (E01) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the A21 and A22 transmission control ECU assembly connectors. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition A22-24 (LIN) - A22-1 (E1) B - BR LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the transmission control ECU assembly may be malfunctioning.
11. CHECK POWER MANAGEMENT CONTROL ECU Disconnect the H3 and H4 power management control ECU connectors. Measure the voltage and resistance according to the value(s) in the table below. HINT: Measure the values on the wire harness side with the connectors disconnected. Tester Connection Wiring Color Terminal Description Condition Specified Condition H3-1 (AM22) - Body ground W - Body ground Auxiliary battery power supply Power switch off 11 to 14 V H4-7 (AM21) - Body ground W - Body ground Auxiliary battery power supply Power switch off 11 to 14 V H3-6 (E1) - Body ground W-B - Body ground Ground Always Below 1 ohms If the result is not as specified, there may be a malfunction in the wire harness. Reconnect the H3 and H4 power management control ECU connectors. Check for pulses according to the value(s) in the table below. Tester Connection Wiring Color Terminal Description Condition Specified Condition H4-11 (LIN2) - H3-6 (E1) B - W-B LIN communication line Power switch on (IG) Pulse generation If the result is not as specified, the power management control ECU may be malfunctioning.

DIAGNOSIS SYSTEM

1. DESCRIPTION The main body ECU (multiplex network body ECU) and certification ECU (smart key ECU assembly) control the LIN communication system. LIN communication system data and Diagnostic Trouble Codes (DTCs) can be read through the Data Link Connector 3 (DLC3). When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform repairs.
2. CHECK DLC3 Check the DLC3. Refer to «GENERAL INFORMATION»(ref-568589-S28103458762013072300000) .
3. INSPECT AUXILIARY BATTERY VOLTAGE Measure the auxiliary battery voltage with the power switch off. Standard Voltage 11 to 14 V If the voltage is below 11 V, recharge or replace the auxiliary battery.

DTC CHECK / CLEAR

1. CHECK DTC Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Body Electrical or Powertrain / Power Source Control, Smart Access or Main Body / Trouble Codes. Check the details of the DTC(s). Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-568820-S18233360872013072300000) .
2. CLEAR DTC Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Body Electrical or Powertrain / Power Source Control, Smart Access or Main Body / Trouble Codes. Clear the DTC(s).

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 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 on (IG). Turn the Techstream on. Enter the following menus: Body Electrical / Main Body / Data List. Read the Data List according to the display on the Techstream. MAIN BODY (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) Tester Display Measurement Item/Range Normal Condition Diagnostic Note Communication D-Door Motor Connection status between power window regulator motor assembly (for driver side) and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. Communication P-Door Motor Connection status between power window regulator motor assembly (for front passenger side) and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. Communication RR-Door Motor Connection status between power window regulator motor assembly (for rear RH side) and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. Communication RL-Door Motor Connection status between power window regulator motor assembly (for rear LH side) and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. Communication Slide Roof*1 Connection status between sliding roof ECU (sliding roof drive gear assembly) and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. Communication Master SW Connection status between multiplex network master switch assembly and main body ECU (multiplex network body ECU)/OK or STOP OK: Connected STOP: Not Connected DTC is output if an error occurs in LIN communication. *1: w/ Sliding Roof System

DIAGNOSTIC TROUBLE CODE CHART

MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

1. *1: w/ Sliding Roof System

CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

1. *2: Although "No Response from Steering Lock ECU" is displayed on the Techstream, this message is shown if the certification ECU (smart key ECU assembly) cannot communicate with the transmission control ECU assembly.

POWER MANAGEMENT CONTROL ECU