Multiplex Communication: Overview Lexus LS IV

SYSTEM DESCRIPTION

1. LIN COMMUNICATION SYSTEM DESCRIPTION The LIN communication system is used for communication between the components below. Each part of the LIN communication system has a component as a control master. Door and Sliding Roof Components That Use LIN Communication Bus HINT: *: Control master Main Body ECU (Driver Side Junction Block)* Master Switch Assembly Front Power Window Regulator Motor Assembly LH Front Power Window Regulator Motor Assembly RH Rear Power Window Regulator Motor Assembly LH Rear Power Window Regulator Motor Assembly RH Sliding Roof Drive Gear Sub-assembly (Sliding Roof ECU) Certification Components That Use LIN Communication Bus HINT: *: Control master Certification ECU (Smart Key ECU)* Main Body ECU (Driver Side Junction Block) Steering Lock Actuator Assembly (Steering Lock ECU) ID Code Box (Immobilizer Code ECU) Rain Sensor Components That Use LIN Communication HINT: *: Control master Front Light ECU (Front Controller)* Rain Sensor Overhead Junction Block Components That Use LIN Communication HINT: *: Control master Luggage Room Junction Block (Rear Junction Block ECU)* Map Light Assembly (Overhead Junction Block) Rear Heater Components That Use LIN Communication HINT: *: Control master Air Conditioning Amplifier Assembly* Rear Power Seat Module Switch Rear Air Conditioning Components That Use LIN Communication HINT: *: Control master Air Conditioning Amplifier Assembly* Infrared Ray Sensor Driver Side Seat Switch Components That Use LIN Communication Bus HINT: *: Control master Outer Mirror Switch* No. 1 Console Switch Front Seat Climate Control ECU LH Front Seat Climate Control ECU RH Rear Seat Switch Components That Use LIN Communication Bus HINT: *: Control master Rear Power Seat Module Switch* Position Control ECU LH Position Control ECU RH Rear Seat Climate Control ECU LH Rear Seat Climate Control ECU RH Seat Vibration System Components That Use LIN Communication HINT: *: Control master Seat Vibration Module Assembly* Seat Vibrator Switch
2. LIN COMMUNICATION SYSTEM DTCs The control master components shown below output LIN communication system DTCs when there is a malfunction in the LIN communication. If a LIN communication stops, the control master of that part of the LIN communication system outputs DTCs. Main Body ECU (Driver Side Junction Block) Certification ECU (Smart Key ECU) Luggage Room Junction Block (Rear Junction Block ECU) Air Conditioning Amplifier Assembly* HINT: *: LIN Communication Between Components Related to Rear Air Conditioning Outer Mirror Switch Rear Power Seat Module Switch

DESCRIPTION

This DTC is output when LIN communication between the master switch and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 1

This DTC is output when LIN communication between the sliding roof drive gear (sliding roof ECU) and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 2

This circuit consists of the infrared ray sensor and the air conditioning amplifier. The infrared ray sensor, which is installed on the rear roof, detects human body temperature and controls the heater and air conditioner "AUTO" mode in 4 zone. Signals are transmitted to the air conditioning amplifier via LIN communication line. This DTC is output when LIN communication between the infrared ray sensor and air conditioning amplifier stop for 10 seconds or more. If the LIN communication system malfunctions, the air conditioning amplifier does not operate even if the infrared ray sensor is normal.

DTC DETECTION CONDITION CHART

HINT

For vehicles with infrared ray sensor only.

Scheme 3

Scheme 4

1. CHECK HARNESS AND CONNECTOR (INFRARED RAY SENSOR - AIR CONDITIONING AMPLIFIER) Disconnect the X13 infrared ray sensor connector. Disconnect the L76 air conditioning amplifier connector. Measure the resistance according to the value(s) in the table below. Standard resistance SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition X13-3 (LIN) - L76-28 (LIN1) Always Below 1 ohms X13-3 (LIN) - Body ground Always 10 kohms or higher L76-28 (LIN1) - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
2. CHECK INFRARED RAY SENSOR (OPERATION) Replace the infrared ray sensor with a new or normally functioning one (see «INFRARED RAY SENSOR» ). Operate the infrared ray sensor to check that it functions normally. OK: Infrared ray sensor function operates normally. NG: REPLACE AIR CONDITIONING AMPLIFIER OK: END (INFRARED RAY SENSOR IS FAULTY)

This DTC is output there is an open, short or ECU communication malfunction between the main body ECU (driver side junction block) and certification ECU (smart key ECU).

DTC DETECTION CONDITION CHART

Scheme 5

This DTC is output when LIN communication between the front power window regulator motor LH and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 6

This DTC is output when LIN communication between the front power window regulator motor RH and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 7

This DTC is output when LIN communication between the rear power window regulator motor RH and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 8

This DTC is output when LIN communication between the rear power window regulator motor LH and main body ECU (driver side junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 9

The main body ECU (driver side junction block) monitors the LIN communication bus between the components related to the door and sliding roof intermittently. DTC B2325 is output when a malfunction in the LIN communication bus between the components related to the door and sliding roof is detected continuously 3 times.

DTC DETECTION CONDITION CHART

Scheme 10

This DTC is output when LIN communication between the luggage room junction block (rear junction block ECU) and map light (overhead junction block) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 11

The certification ECU (smart key ECU) monitors the LIN communication bus between the components related to the certification intermittently. DTC B2785 is output when a malfunction in the LIN communication bus between the components related to the certification is detected continuously 3 times.

DTC DETECTION CONDITION CHART

Scheme 12

This DTC is output when LIN communication between the certification ECU (smart key ECU) and steering lock actuator assembly (steering lock ECU) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 13

This DTC is output when LIN communication between the certification ECU (smart key ECU) and ID code box (immobilizer code ECU) stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 14

This DTC is output when LIN communication between the position control ECU RH and rear power seat module switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 15

This DTC is output when LIN communication between the position control ECU LH and rear power seat module switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 16

This DTC is output when LIN communication between the outer mirror switch and No. 1 console switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 17

This DTC is output when LIN communication between the front seat climate control ECU RH and outer mirror switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 18

This DTC is output when LIN communication between front seat climate control ECU LH and outer mirror switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 19

This DTC is output when LIN communication between the rear seat climate control ECU RH and rear power seat module switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 20

This DTC is output when LIN communication between the rear seat climate control ECU LH and rear power seat module switch stops for 10 seconds or more.

DTC DETECTION CONDITION CHART

Scheme 21

The LIN communication of the components related to the rain sensor occurs between the rain sensor and front light ECU (front controller).

Scheme 22

The LIN communication of the components related to the rear heater occurs between the air conditioning amplifier (A/C ECU) and rear power sear module switch.

Scheme 23

The seat vibrator module receives power from the battery, and operates the seat vibrator. Also, the seat vibrator module and seat vibrator switch are controlled through communication signals. If an error is detected, all system operations stop and only SW1 can be operated (all other switches cannot be operated). After the error is corrected, the system enters stop mode.

DETECTION CONDITION CHART

Scheme 24

Scheme 25

Scheme 26

Scheme 27

1. CHECK BLINKING CONDITION OF LED7 5 seconds after the seat vibrator switch SW1 is pressed, check if LED7 blinks (see «SYSTEM DIAGRAM»(/lexus/ls/iv-2006-2012/remont/seats/#seat) ). OK: LED7 blinds. NG: Go to step 3 OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (SEAT VIBRATOR MODULE - BATTERY AND BODY GROUND) Disconnect the S29 seat vibrator module connector. Measure the voltage and resistance according to the values in the table below. Standard voltage VOLTAGE SPECIFICATION Tester Connection Switch Condition Specified Condition S29-1 IG) - Body ground Engine switch on (IG) 11 to 14 V Standard resistance SPECIFIED CONDITION CHART Tester Connection Switch Condition Specified Condition S29-8 (GND) - Body ground Always Below 1 ohms NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE SEAT VIBRATOR MODULE ASSEMBLY (See «REMOVAL»(/lexus/ls/iv-2006-2012/remont/seats/#seat) )
3. CHECK BLINKING CONDITION OF LED6 5 seconds after the seat vibrator switch SW1 is pressed, check if LED6 blinks (see «SYSTEM DIAGRAM»(/lexus/ls/iv-2006-2012/remont/seats/#seat) ). OK: LED6 blinks. NG: Go to «SEAT VIBRATION SYSTEM»(/lexus/ls/iv-2006-2012/remont/seats/#seat) OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (SEAT VIBRATOR SWITCH - BATTERY AND BODY GROUND) Disconnect the Y2 switch connector. Measure the voltage and resistance according to the values in the table below. Standard voltage VOLTAGE SPECIFICATION Tester Connection Switch Condition Specified Condition Y2-1 (IG) - Body ground Engine switch on (IG) 11 to 14 V Standard resistance SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition Y2-5 (GND) - Body ground Always Below 1 ohms NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
5. CHECK AND REPLACE HARNESS AND CONNECTOR (SEAT VIBRATOR SWITCH - SEAT VIBRATOR MODULE) Disconnect the S29 seat vibrator module connector. Disconnect the Y2 switch connector. Measure the resistance according to the values in the table below. Standard resistance Result: SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition Y2-3 (MPX) - S29-3 (LIN) Always Below 1 ohms NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
6. CHECK SEAT VIBRATOR SWITCH (OPERATION) Replace the seat vibrator switch with a new or normally operating one. Perform an operation inspection. OK: Seat vibrator operates normally. NG: REPLACE SEAT VIBRATOR MODULE ASSEMBLY (See «REMOVAL»(/lexus/ls/iv-2006-2012/remont/seats/#seat) ) OK: END (SEAT VIBRATOR SWITCH IS DEFECTIVE)

The outer mirror switch monitors the LIN communication bus between the components related to the switches on the driver side seat.

HINT

DTC U1127, U1128 and U1129 are output simultaneously when: 1) there is an open or short in the LIN communication bus between the switches on the driver side seat, and 2) their LIN communication bus stops.

Scheme 28

The rear power seat module switch monitors the LIN communication bus between the components related to the switches on the rear seat.

HINT

DTC U0211, U0246, U1130 and U1131 are output simultaneously when: 1) there is an open or short in the LIN communication bus between the switches on the rear seat, and 2) their LIN communication bus stops.

Scheme 29

See also:
• CAN COMMUNICATION SYSTEM
• REMOVAL
• SYSTEM DIAGRAM