Multiplex Communication: Diagnosis Lexus RX II facelift

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

1. Use this procedure to troubleshoot the multiplex communication system.
2. The intelligent tester should be used in step 2.

1. VEHICLE BROUGHT TO WORKSHOP
2. DTC CHECK Check for DTCs and note any codes that are output (See «DTC CHECK/CLEAR»(ref-236026-S40908994272006062900000) ). Delete the DTC. Recheck for DTCs. Try to prompt the DTC by simulating the original activity that the DTC suggests. If the DTC does not reoccur, proceed to A. If the DTC reoccurs, proceed to B. B: Go to step 4 A: Go to next step
3. OVERALL ANALYSIS AND TROUBLESHOOTING See «SYSTEM DIAGRAM»(ref-236026-S34149496872006062900000) See «TERMINALS OF ECU»(ref-236026-S31384667322006062900000)
4. ADJUST, REPAIR OR REPLACE
5. CONFIRMATION TEST END

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1. INSPECT INSTRUMENT PANEL J/B ASSEMBLY (MULTIPLEX NETWORK BODY ECU) Disconnect the B5 ECU, 1D, 1E, 1F, 1M and 1R J/B connectors. Check the voltage and resistance between each terminal of the wire harness side connectors. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BECU (1D-10) - Body ground L-B - Body ground +B (ECUB) power supply Constant 10 to 14 V BECU (1F-1) - Body ground SB - Body ground +B (ECUB) power supply Constant 10 to 14 V MPX1 (1E-7) - Body ground BR - Body ground MPX line Constant 10 kohms or higher MPX1 (1R-9) - Body ground LG - Body ground MPX line Constant 10 kohms or higher MPX2 (B5-21) - Body ground GR - Body ground MPX line Constant 10 kohms or higher GND1 (1F-10) - Body ground W-B - Body ground Ground Constant Below 1 ohms GND2 (1M-9) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
2. CHECK INTEGRATION SWITCH (w/o LEXUS NAVIGATION SYSTEM) Disconnect the C4 switch connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (C4-1) - GND (C4-7) O - W-B +B (+B) power supply Constant 10 to 14 V MPX+ (C4-5) - Body ground L - Body ground MPX line Constant 10 kohms or higher MPX- (C4-12) - Body ground GR - Body ground MPX line Constant 10 kohms or higher GND (C4-7) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
3. CHECK NETWORK GATEWAY ECU (w/ LEXUS NAVIGATION SYSTEM) Disconnect the G3 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BATT (G3-8) - GND (G3-14) O - W-B +B (BATT) power supply Constant 10 to 14 V MPD1 (G3-4) - Body ground L - Body ground MPX line Constant 10 kohms or higher MPD2 (G3-11) - Body ground GR - Body ground MPX line Constant 10 kohms or higher CG (G3-7) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
4. CHECK ECM Disconnect the E5, E6 and E7 ECM connectors. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BATT (E5-3) - E1 (E7-1) B - BR +B (BATT) power supply Constant 10 to 14 V IGSW (E5-9) - E1 (E7-1) G - BR Ignition Switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V +B (E5-1) - E1 (E7-1) L-B - BR +B (+B) power supply Ignition Switch OFF --> ON 0 V --> 10 to 14 V +B2 (E5-2) - E1 (E7-1) L-B - BR +B (+B2) power supply Ignition Switch OFF --> ON 0 V --> 10 to 14 V MPX1 (E6-18) - Body ground R - Body ground MPX line Constant 10 kohms or higher MPX2 (E6-29) - Body ground O - Body ground MPX line Constant 10 kohms or higher E1 (E7-1) - Body ground BR - Body ground Ground Constant Below 1 ohms ME01 (E7-4) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
5. CHECK TRANSPONDER KEY ECU ASSEMBLY Disconnect the T9 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (T9-1) - GND (T9-14) V - W-B +B (CPUB) power supply Constant 10 to 14 V MPX1 (T9-4) - Body ground O - Body ground MPX line Constant 10 kohms or higher MPX2 (T9-5) - Body ground R - Body ground MPX line Constant 10 kohms or higher GND (T9-14) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
6. CHECK MULTIPLEX TILT & TELESCOPIC ECU Disconnect the T4 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (T4-2) - GND (T4-11) Y - W-B +B (+B) power supply Constant 10 to 14 V ECUB (T4-9) - GND (T4-11) SB - W-B +B (ECUB) power supply Constant 10 to 14 V MPX1 (T4-5) - Body ground GR - Body ground MPX line Constant 10 kohms or higher MPX2 (T4-14) - Body ground O - Body ground MPX line Constant 10 kohms or higher GND (T4-11) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
7. CHECK A/C AMPLIFIER (A/C ECU) Disconnect the A8 amplifier connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (A8-2) - GND (A8-6) SB - W-B +B (+B) power supply Constant 10 to 14 V MPX+ (A8-3) - Body ground BR - Body ground MPX line Constant 10 kohms or higher MPX- (A8-4) - Body ground GR - Body ground MPX line Constant 10 kohms or higher GND (A8-6) - Body ground W-B - Body ground Ground Constant 10 kohms or higher If the result is not as specified, there may be a malfunction on the wire harness side.
8. CHECK OUTER MIRROR CONTROL ECU ASSEMBLY (PASSENGER SIDE) Disconnect the R27 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (R27-7) - GND (R27-1) L-B - W-B +B (CPUB) power supply Constant 10 to 14 V BDR (R27-3) - GND (R22-1) G - W-B +B (BDR) power supply Constant 10 to 14 V MPX1 (R27-6) - Body ground L - Body ground MPX line Constant 10 kohms or higher GND (R27-1) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
9. CHECK OUTER MIRROR CONTROL ECU ASSEMBLY (DRIVER SIDE) Disconnect the R26 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition CPUB (R26-7) - GND (R21-1) L-B - W-B +B (CPUB) power supply Constant 10 to 14 V BDR (R26-3) - GND (R21-1) G - W-B +B (BDR) power supply Constant 10 to 14 V MPX1 (R26-6) - Body ground R - Body ground MPX line Constant 10 kohms or higher GND (R26-1) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
10. CHECK WINDSHIELD WIPER RELAY ASSEMBLY (WIPER ECU) Disconnect the A28 relay connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (A28-8) - E (A28-12) SB - W-B +B (+B) power supply Constant 10 to 14 V MPX1 (A28-1) - Body ground BR - Body ground MPX line Constant 10 kohms or higher E (A28-12) - Body ground W-B - Body ground Ground Constant 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 & SWITCH (POWER SEAT ECU) Disconnect the P32 and P33 ECU connectors. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition +B (P33-5) - GND (P33-1) LG - W-B +B (+B) power supply Constant 10 to 14 V SYSB (P32-8) - GND (P33-1) GR - W-B +B (SYSB) power supply Constant 10 to 14 V IG (P32-4) - GND (P33-1) Y - W-B Ignition switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V MPX1 (P32-1) - Body ground W - Body ground MPX line Constant 10 kohms or higher GND (P33-1) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
12. CHECK MULTIPLEX NETWORK DOOR ECU BACK (BACK DOOR ECU) Disconnect the P13 and P14 ECU connectors. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (P14-2) - GND (P14-8) Y - W-B +B (+B) power supply Constant 10 to 14 V ECUB (P13-10) - GND (P14-8) BR - W-B +B (ECUB) power supply Constant 10 to 14 V IG (P13-9) - GND (P14-8) GR - W-B Ignition switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V MPX1 (P13-22) - Body ground SB - Body ground MPX line Constant 10 kohms or higher GND (P14-8) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
13. CHECK POWER WINDOW REGULATOR MASTER SWITCH ASSEMBLY Disconnect the P22 switch connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition BDR (P22-10) - GND (P22-2) G - W-B +B (+BDR) power supply Constant 10 to 14 V CPUB (P22-9) - GND (P22-2) L-B - W-B +B (CPUB) power supply Constant 10 to 14 V MPX1 (P22-7) - Body ground R - Body ground MPX line Constant 10 kohms or higher MPX2 (P22-8) - Body ground GR - Body ground MPX line Constant 10 kohms or higher GND (P22-2) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
14. CHECK COMBINATION METER ASSEMBLY Disconnect the C8 and C9 meter connectors. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (C8-15) - GND (C8-1) SB - W-B +B (B) power supply Constant 10 to 14 V ECUB (C8-16) - GND (C8-1) O - W-B +B (ECUB) power supply Constant 10 to 14 V MPX+ (C8-5) - Body ground) Y - Body ground MPX line Constant 10 kohms or higher MPX- (C9-4) - Body ground V - Body ground MPX line Constant 10 kohms or higher GND (C8-1) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
15. CHECK AIRBAG SENSOR ASSEMBLY (AIRBAG ECU) Disconnect the A20 sensor connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition IG2 (A20-5) - E1 (A20-27) B - W-B Ignition Switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V MPX1 (A20-24) - Body ground BR - Body ground MPX line Constant 10 kohms or higher MPX2 (A20-22) - Body ground) BR - Body ground MPX line Constant 10 kohms or higher E1 (A20-27) - Body ground W-B - Body ground Ground Constant Below 1 ohms E2 (A20-28) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
16. CHECK SLIDING ROOF DRIVE GEAR ASSEMBLY (SLIDING ROOF ECU (STANDARD TYPE)) Disconnect the M12 gear connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (M12-1) - E (M12-7) P - W-B +B (B) power supply Constant 10 to 14 V ECUB (M12-5) - E(M12-7) SB - W-B +B (ECUB) power supply Constant 10 to 14 V MPX1 (M12-10) - Body ground R - Body ground MPX line Constant 10 kohms or higher E (M12-7) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
17. CHECK SLIDING ROOF DRIVE GEAR ASSEMBLY (SLIDING ROOF ECU (MULTI-PANEL MOON ROOF TYPE)) Disconnect the M12 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition B (M12-4) - E (M12-8) P - W-B +B (B) power supply Constant 10 to 14 V ECUB (M12-10) - E(M12-8) SB - W-B +B (ECUB) power supply Constant 10 to 14 V MPX1 (M12-5) - Body ground R - Body ground MPX line Constant 10 kohms or higher E (M12-8) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
18. CHECK RAIN SENSOR Disconnect the R7 sensor connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition SIG (R7-1) - ES (R7-3) P - W-B +B (SIG) power supply Constant 10 to 14 V MPX1 (R7-2) - Body ground V - Body ground MPX line Constant 10 kohms or higher ES (R7-3) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.
19. CHECK HEADLIGHT SWIVEL ECU (AFS ECU) Disconnect the A14 ECU connector. Check the voltage and resistance of each terminal of the wire harness side connector. Standard TERMINAL DESCRIPTION SPECIFIED CONDITION CHART Symbols (Terminal No.) Wiring Color Terminal Description Condition Specified Condition IGS (A14-12) - E1 (A14-1) P - W-B Ignition switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V >IG (A14-2) - E1 (A14-1) P - W-B Ignition switch Ignition Switch OFF --> ON 0 V --> 10 to 14 V MPX1 (A14-5) - Body ground W - Body ground MPX line Constant 10 kohms or higher E1S (A14-11) - Body ground W-B - Body ground Ground Constant Below 1 ohms If the result is not as specified, there may be a malfunction on the wire harness side.

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1. DIAGNOSIS SYSTEM Inspect the DLC3. HINT: The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format. TESTER CONNECTION SPECIFIED CONDITION CHART Terminal No. Condition Specified Condition 7 (Bus + line) - 5 (Signal ground) During communication Pulse generation 4 (Chassis ground) - Body ground Constant Below 1 ohms 5 (Signal ground) - Body ground Constant Below 1 ohms 16 (B+) - Body ground Constant 9 to 14 V HINT: If the display shows UNABLE CONNECT TO VEHICLE when you have connected the cable of the intelligent tester to the DLC3, turned the ignition switch ON and operated the intelligent tester, there is a problem on the vehicle side or tester side. If communication is normal when the tester is connected to another vehicle, inspect the DLC3 of the original vehicle. If communication is still impossible when the tester is connected to another vehicle, the problem is probably in the tester itself, so consult the Service Department listed in the tester's instruction manual. Check the battery voltage. Battery voltage: 11 to 14 V If voltage is below 11V, recharge the battery before proceeding.

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1. CHECK DTC Connect the intelligent tester to the DLC3. Turn the ignition switch ON. Read DTCs by following the prompts on the tester screen. HINT: Refer to the intelligent tester operator's manual for further details.
2. CLEAR DTC Connect the intelligent tester to the DLC3. Turn the ignition switch ON. Erase the DTCs following the prompts on the tester screen. HINT: Refer to the intelligent tester operator's manual for further details.

DIAGNOSTIC TROUBLE CODE CHART

If a malfunction code is displayed during the DTC check, check the circuit listed for that code in the chart below (Proceed to the link given for that circuit).

DIAGNOSTIC TROUBLE CODE CHART