Multiplex Communication (Diagnostics - Introduction): Diagnosis Lexus GS III рестайлинг

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

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

1. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step
2. CHECK FOR DTC* Check for DTCs and note any codes that are output. Delete the DTC. Recheck for DTCs. Try to prompt the DTC by simulating the original activity that the DTC suggests. RESULT Result Proceed to DTC does not reoccur A DTC reoccurs B B --> Go to step 4 A: Go to next step
3. OVERALL ANALYSIS AND TROUBLESHOOTING Terminals of ECU. Refer to «TERMINALS OF ECU»(ref-386979-S26490834512011022400000) . NEXT: Go to next step
4. ADJUST, REPAIR OR REPLACE NEXT: Go to next step
5. CONFIRMATION TEST NEXT --> END

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1. CHECK NETWORK GATEWAY ECU Disconnect the K66 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BATT (K66-10) - GND (K66-24) G - W-B +B (BATT) power supply Always 10 to 14 V IG (K66-1) - Body ground B - Body ground Ignition power supply Power switch ON (IG) 10 to 14 V ACC (K66-2) - Body ground V - Body ground ACC power supply Power switch ON (ACC) 10 to 14 V SIL (K66-7) - Body ground BE - Body ground Bus "+" line During transmission Pulse generation MPI1 (K66-4) - Body ground LG - Body ground MPX line Always 10 kohms or higher MPI2 (K66-13) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPL1 (K66-5) - Body ground W - Body ground MPX line Always 10 kohms or higher MPL2 (K66-14) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPD1 (K66-3) - Body ground P - Body ground MPX line Always 10 kohms or higher MPD2 (K66-12) - Body ground SB - Body ground MPX line Always 10 kohms or higher GND (K66-24) - 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.
2. CHECK ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK (FRONT CONTROLLER) Disconnect the 1X and 1Y junction block connectors. Measure the voltage and resistance of the wire harness side connectors. Symbol (Terminal No.) Wiring Color Terminal Description Condition Specified Condition 1Y-4 - 1X-1 G-R - W-B +B (FMB3) power supply Always 10 to 14 V 1X-5 - 1X-1 GR - W-B MPX line Always 10 kohms or higher 1X-6 - 1X-1 GR-L - W-B MPX line Always 10 kohms or higher 1X-1 - 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 MAIN BODY ECU LH (COWL SIDE JUNCTION BLOCK LH) Disconnect the A30, V3, PA, PD and PL ECU connectors. Measure the resistance and voltage of the wire harness side connectors. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition MPXB (PL-1) - GND (PA-14) G-R - W-B +B (MPXB) power supply Always 10 to 14 V MPX1 (V3-15) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPX4 (A30-6) - Body ground G-R - Body ground*1 GR-L - Body ground*2 MPX line Always 10 kohms or higher GND (PA-14) - Body ground W-B - Body ground Ground Always Below 1 ohms SGND (PD-8) - Body ground W-B - Body ground Ground Always Below 1 ohms *1: w/ Adaptive Front-Lighting System *2: w/o Adaptive Front-Lighting System If the result is not as specified, there may be a malfunction on the wire harness side.
4. CHECK MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) Disconnect the DA, DD, DK and K68 ECU connectors. Measure the resistance and voltage of the wire harness side connectors. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BECU (DK-5) - GND2 (DD-7) G-R - W-B +B (MPX-B) power supply Always 10 to 14 V MPX1 (DA-26) - GND2 (DD-7) GR - W-B MPX line Always 10 kohms or higher MPX2 (K68-21) - GND2 (DD-7) G - W-B MPX line Always 10 kohms or higher GSW (DA-7) - GND2 (DD-7) B - W-B MPX line Always 10 kohms or higher GND2 (DD-7) - 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 NO. 1 JUNCTION BLOCK (MULTIPLEX NETWORK REAR ECU) Disconnect the LB, LC and LF junction block connectors. Measure the resistance and voltage of the wire harness side connectors. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition ECUB (LC-15) - Body ground B - Body ground +B (ECUB) power supply Always 10 to 14 V MPX1 (LC-21) - Body ground BR - Body ground MPX line Always 10 kohms or higher MPX2 (LC-31) - Body ground) GR - Body ground MPX line Always 10 kohms or higher PGND (LF-1) - Body ground W-B - Body ground Ground Always Below 1 ohms SG (LC-3) - 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.
6. CHECK MULTIPLEX NETWORK FRONT DOOR ECU LH (FRONT DOOR ECU LH) Disconnect the M9 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (M9-4) - Body ground LG - Body ground +B (CPUB) power supply Always 10 to 14 V BDR (M9-6) - Body ground L - Body ground +B (BDR) power supply Always 10 to 14 V MPX1 (M9-8) - Body ground P - Body ground MPX line Always 10 kohms or higher MPX2 (M9-9) - Body ground L - Body ground MPX line Always 10 kohms or higher GND (M9-1) - 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.
7. CHECK MULTIPLEX NETWORK FRONT DOOR ECU RH (FRONT DOOR ECU RH) Disconnect the M4 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (M4-4) - Body ground LG - Body ground +B (CPUB) power supply Always 10 to 14 V BDR (M4-6) - Body ground L - Body ground +B (BDR) power supply Always 10 to 14 V MPX1 (M4-8) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPX2 (M4-9) - Body ground P - Body ground MPX line Always 10 kohms or higher GND (M4-1) - 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.
8. CHECK MULTIPLEX NETWORK REAR DOOR ECU LH (REAR DOOR ECU LH) Disconnect the O7 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (O7-4) - Body ground BR - Body ground +B (CPUB) power supply Always 10 to 14 V BDR (O7-6) - Body ground L - Body ground +B (BDR) power supply Always 10 to 14 V MPX1 (O7-8) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPX2 (O7-9) - Body ground P - Body ground MPX line Always 10 kohms or higher GND (O7-1) - 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.
9. CHECK MULTIPLEX NETWORK REAR DOOR ECU RH (REAR DOOR ECU RH) Disconnect the O3 ECU connector. Measure the voltage the resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (O3-4) - Body ground G - Body ground +B (CPUB) power supply Always 10 to 14 V BDR (O3-6) - Body ground L - Body ground +B (BDR) power supply Always 10 to 14 V MPX1 (O3-8) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPX2 (O3-9) - Body ground P - Body ground MPX line Always 10 kohms or higher GND (O3-1) - 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.
10. CHECK POSITION CONTROL ECU AND SWITCH (for Driver Side) Disconnect the b7 and b8 ECU connectors. Measure the voltage and the resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (b8-5) - GND (b8-1) L - W-B +B power supply Always 10 to 14 V SYSB (b7-8) - Body ground G - Body ground +B (SYSB) power supply Always 10 to 14 V MPX1 (b7-1) - Body ground GR - Body ground MPX line Always 10 kohms or higher GND (b8-1) - 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.
11. CHECK POSITION CONTROL ECU AND SWITCH (for Front Passenger Side) Disconnect the a7 and a6 ECU connectors. Measure the voltage and the resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (a6-5) - GND (a6-1) L - W-B +B power supply Always 10 to 14 V SYSB (a7-8) - Body ground R - Body ground +B (SYSB) power supply Always 10 to 14 V MPX1 (a7-1) - Body ground P - Body ground MPX line Always 10 kohms or higher GND (a6-1) - 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.
12. CHECK AIR CONDITIONING NO. 2 AMPLIFIER ASSEMBLY (A/C ECU) Disconnect the K52 amplifier connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (K52-1) - GND (K52-20) L - W-B +B power supply Always 10 to 14 V IG+ (K52-21) - Body ground W - Body ground Power switch signal (IG) Power switch ON (IG) 10 to 14 V MPX+ (K52-30) - Body ground SB - Body ground MPX line Always 10 kohms or higher MPX- (K52-31) - Body ground Y - Body ground MPX line Always 10 kohms or higher GND (K52-20) - 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.
13. CHECK CENTER AIRBAG SENSOR Disconnect the K44 sensor connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition IG2 (K44-21) - E1 (K44-25) B - W-B Power switch signal (IG) Power switch ON (IG) 10 to 14 V MPX1 (K44-13) - Body ground R - Body ground MPX line Always 10 kohms or higher MPX2 (K44-22) - Body ground R - Body ground MPX line Always 10 kohms or higher E1 (K44-25) - Body ground W-B - Body ground Ground Always Below 1 ohms E2 (K44-26) - 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.
14. CHECK COMBINATION METER (METER ECU) Disconnect the K31 meter connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (K31-21) - Body ground P - Body ground +B (B) power supply Always 10 to 14 V B (K31-22) - Body ground L - Body ground +B (B) power supply Always 10 to 14 V MPX+ (K31-25) - Body ground GR - Body ground MPX line Always 10 kohms or higher MPX- (K31-5) - Body ground SB - Body ground MPX line Always 10 kohms or higher E2 (K31-40) - 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.
15. CHECK SLIDING ROOF DRIVE GEAR (SLIDING ROOF CONTROL ECU) Disconnect the W7 drive gear connector. Measure the voltage and the resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (W7-5) - E (W7-7) L - W-B +B (B) power supply Always 10 to 14 V MPX1 (W7-10) - Body ground GR - Body ground MPX line Always 10 kohms or higher E (W7-7) - 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.
16. CHECK MULTIPLEX TILT AND TELESCOPIC ECU Disconnect the K27 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition ECUB (K27-9) - GND (K27-11) R - W-B +B (ECUB) power supply Always 10 to 14 V +B (K27-2) - GND (K27-11) L - W-B +B (+B) power supply Always 10 to 14 V MPX1 (K27-5) - Body ground GR - Body ground MPX line Always 10 kohms or higher GND (K27-11) - 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 COMBINATION SWITCH (WINDSHIELD WIPER SWITCH) Disconnect the K22 switch connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminals No.) Wiring Color Terminal Description Condition Specified Condition B (K22-1) - E (K22-5) GR - W-B +B (B) power supply Always 10 to 14 V MPX1 (K22-6) - Body ground G - Body ground MPX line Always 10 kohms or higher MPX2 (K22-7) - Body ground BE - Body ground MPX line Always 10 kohms or higher E (K22-5) - 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 MULTIPLEX NETWORK MASTER SWITCH Disconnect the Q13 switch connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (Q13-15) - E (Q13-12) P - W-B +B (CPUB) power supply Always 10 to 14 V E (Q13-12) - Body ground W-B - Body ground Ground Always Below 1 ohms MPX1 (Q13-3) - E (Q13-12) GR - W-B MPX line Always Below 1 ohms MPX2 (Q13-2) - E (Q13-12) P - W-B MPX line Always Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
19. CHECK POWER SOURCE CONTROL ECU Disconnect the K73 ECU connector. Measure the voltage and resistance of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition AM1 (K73-33) - GND2 (K73-6) BE - W-B +B (AM1) power supply Always 10 to 14 V AM2 (K73-12) - GND2 (K73-6) BR - W-B +B (AM2) power supply Always 10 to 14 V MPX1 (K73-7) - Body ground LG - Body ground MPX line Always 10 kohms or higher MPX2 (K73-24) - Body ground P - Body ground MPX line Always 10 kohms or higher GND2 (K73-6) - 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.
20. CHECK CERTIFICATION ECU Disconnect the U28 ECU connector. Measure the resistance and voltage of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B1 (U28-1) - E (U28-17) R - W-B B power supply Always 10 to 14 V MPX1 (U28-27) - E (U28-17) BR - W-B MPX line Always 10 kohms or higher MPX2 (U28-28) - E (U28-17) GR - W-B MPX line Always 10 kohms or higher E (U28-17) - 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.
21. CHECK TIRE PRESSURE WARNING ECU Disconnect the K45 ECU connector. Measure the resistance and voltage of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition IG (K45-1) - GND (K45-7) G - W-B Power switch signal (IG) Always 10 to 14 V MPX1 (K45-6) - GND (K45-7) LG - W-B MPX line Always 10 kohms or higher MPX2 (K45-12) - GND (K45-7) GR - W-B MPX line Always 10 kohms or higher GND (K45-7) - 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.
22. CHECK AFS ECU Disconnect the A29 ECU connector. Measure the resistance and voltage of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition E1 (A29-1) - Body ground W-B - Body ground Ground Always Below 1 V IG (A29-2) - E1 (A29-1) B - W-B Power source circuit (to power switch) Power switch OFF Below 1 V Power switch ON (IG) 10 to 14 V MPX1 (A29-5) - E1 (A29-1) G-R - W-B MPX communication signal Power switch ON (IG) Signal waveform MPX2 (A29-6) - E1 (A29-1) GR-L - W-B MPX communication signal Power switch ON (IG) Signal waveform If the result is not as specified, there may be a malfunction on the wire harness side.
23. CHECK CLEARANCE WARNING ECU Disconnect the A38 ECU connector. Measure the resistance and voltage of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition IG (A38-8) - E (A38-27) G-Y - W-B Power switch signal (IG) Power switch ON (IG) 10 to 14 V E (A38-27) - Body ground W-B - Body ground ECU ground Always Below 1 ohms M+ (A38-26) - E (A38-27) GR - W-B BEAN communication Power switch ON (IG), Clearance sonar main switch ON Pulse generation If the result is not as specified, there may be a malfunction on the wire harness side.
24. CHECK MAYDAY ECU Disconnect the U45 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (U45-1) - Body ground GR - Body ground B power supply Always 10 to 14 V E (U45-12) - Body ground W-B - Body ground ECU ground Always Below 1 ohms MPX1 (U45-23) - Body ground GR - Body ground MPX communication signal Always 10 kohms or higher If the result is not as specified, there may be a malfunction on the wire harness side.

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1. DESCRIPTION The network gateway ECU controls the functions of the multiplex communication system of the vehicle. Data of the multiplex communication system and the Diagnostic Trouble Codes (DTC) can be read through the Data Link Connector 3 (DLC3) of the vehicle.
2. CHECK DLC3 The ECU uses ISO 15765-4 for communication. 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 transmission 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 69 ohms CANH (6) - CG (4) HIGH-level CAN bus line Power switch OFF* 200 ohms or higher CANL (14) - CG (4) LOW-level CAN bus line Power switch OFF* 200 ohms or higher CANH (6) - BAT (16) HIGH-level CSN bus line Power switch OFF* 6 kohms or higher CANL (14) - BAT (16) LOW-level CSN bus line Power switch OFF* 6 kohms 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 cable of the Techstream to the DLC3, turn the power switch ON (IG) and attempt to use the Techstream. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the Techstream. If communication is normal when the Techstream is connected to another vehicle, inspect the DLC3 of the original vehicle. If communication is still not possible when the Techstream is connected to another vehicle, the problem may be in the Techstream itself. Consult the Service Department listed in the Techstream's instruction manual.
3. INSPECT BATTERY VOLTAGE Standard voltage 11 to 14 V If the voltage is below 11 V, recharge or replace the battery before proceeding.

DTC CHECK / CLEAR

1. CHECK DTC Connect the Techstream to the DLC3. Turn the power switch ON (IG). Read DTCs on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details.
2. CLEAR DTC Connect the Techstream to the DLC3. Turn the power switch ON (IG). Erase the DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details.

DIAGNOSTIC TROUBLE CODE CHART

NETWORK GATEWAY ECU

See also:
• DTC B1200: MPX Body ECU Stop