Multiplex Communication System: Other Lexus GS II рестайлинг

Communication Outline

Communication is implemented among the body No. 1 and No. 2, driver door, front passenger door, LH rear door, RH rear door, center air bag sensor assembly, gateway, tilt and telescopic, A/C control assembly, moon roof, power seat and engine control ECUs.

Upon receiving signals from applicable switches such as the door lock control switch or door courtesy light switch, each ECU determines the conditions of the switches as well as of the doors, and after converting this information into digital signals, outputs them to other ECUs via serial data communication. The ECU that receives these digital signals determines the conditions of the switches and doors so that it can implement various controls such as to activate a door lock motor.

However, if there are no changes in the input signals because no doors were opened and no switches were used within 30 seconds, the body ECU interrupts the communication to save electricity. Following this interruption, any changes in the input signals will cause the communication to resume.

PRE-CHECK

1. Diagnosis System - Each ECU of this vehicle is connected by communication bus and it transmits each signal by communication. (Scheme 11) This communication bus is self-diagnosed by body ECU No. 1 and it memorizes DTC when it detects communication stop to ECU or communication bus +B (battery voltage) short or GND short. There is a possibility that body ECU No. 1 cannot self-diagnose accurately unless it doesn't work normal. So note that the troubleshooting of the body electrical system should be done after confirming if the body ECU No. 1 and open door indicator works normal by the Basic Inspection. See step 2. If a DTC of ECU communication stop is output, there is a possibility of connector disconnection or 2 communication buses open. (Scheme 12) It will not become abnormal with only 1 communication bus open. If 2 communication buses are open at the position, DTC of ECU communication stop between those 2 buses is output. (Scheme 13)
2. Basic Inspection - Inspect body ECU No. 1 operation. With this inspection, body ECU No. 1 Central Processing Unit (CPU) can be diagnosed if it works normal or not. Check if the luggage compartment door opener works normal. If the results are OK, go to step 3. If the results are not good, go to the next step. Check the luggage compartment door opener system (except body ECU No. 1). See «POWER DOOR LOCKS, TRUNK LID & FUEL DOOR RELEASE»(ref-152941) article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT. If the results are OK, replace the body ECU No. 1. See «BODY ECU NO. 1»(ref-152690-S23433460862003021900000) under REMOVAL & INSTALLATION. If the results are not good, repair or replace the malfunction part.
3. OPEN DOOR Indicator Light Inspection - Check if the open door indicator light is turned on when either door is open. If the open door indicator light is not turned on, a DTC will not be output. If the results are OK, retrieve DTCs using the OPEN DOOR indicator light. See «USING OPEN DOOR INDICATOR LIGHT»(ref-152690-S04907618012003022000000) under RETRIEVING DIAGNOSTIC TROUBLE CODES. If the results are not good, repair the open door indicator light. See «INSTRUMENT PANEL»(ref-153134) article in ACCESSORIES & EQUIPMENT.

Scheme 11

Scheme 12

Scheme 13

Using OPEN DOOR Indicator Light

1. Using the Diagnosis Check Wire (SST 09843-18020), connect terminals Tc and E1 of the DLC1 located in the driver side of the engine compartment near the engine room junction block No. 3. (Scheme 14) Turn the ignition switch ON. Read the DTC on the open door indicator light.
2. As an example, the blinking patterns for codes; normal, 12, and 11 and 12. (Scheme 15) Check for the problem using the DTC table. See «DIAGNOSTIC TROUBLE CODE INDEX»(ref-152690-S04339663422003021900000) table. After completing the check, turn the ignition switch off, and disconnect terminals Tc and E1.

Scheme 14

Scheme 15

Using Hand-Held Tester

Note. Always record DTCs during retrieval.

Note. An OBD II scan tool complying with SAE J1978 can be used if Lexus hand-held tester is not available.

Prepare the hand-held tester. Connect the hand-held tester to the DLC3. (Scheme 16) Turn the ignition switch ON and switch the hand-held tester main switch ON. Use the hand-held tester to check the DTCs, note them down. For operating instructions, see the hand-held tester instruction manual. See DIAGNOSTIC TROUBLE CODE INDEX table to confirm the details of the DTCs.

Scheme 16

TERMINALS OF ECU

For ECU connector views (Scheme 17)- (Scheme 28).

Scheme 17

Scheme 18

Scheme 19

Scheme 20

Scheme 21

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

ENGINE CONTROL MODULE (ECM)

Note. Wipe any water off on the ECM cover and the circumference. Procedure should be done indoors where it is dry. Do not put any water into the inside of the engine control module (connector part or screw part). When exchanging ECM, check that there is no trash and foreign objects stuck in the ECM box side (adhesive side).