Multiplex Communication System - Diagnostics: Wiring Lexus GS III

WIRING DIAGRAM

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Scheme 118

1. Check front passenger door ECU. CHECK: Check if the front passenger door window glass auto up. HINT: With this inspection, the front passenger door ECU CPU can be diagnosed if it works normally or not. NG: Replace the front passenger door ECU. OK: Go to next step.
2. Check wire harness PREPARATION: Disconnect connector of body ECU No. 1, "F11" of passenger door ECU and "R13" of rear right door ECU. CHECK: Check continuity between terminals MPX2 of body ECU No. 1 and MPX2 of passenger door ECU. Check continuity between terminals MPX1 of passenger door ECU and MPX2 of rear right door ECU. OK: There is a continuity in wire harness of both (a) and (b) or (a) or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the passenger door ECU.

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Scheme 119

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Scheme 128

1. Check the communication circuit inside sliding roof ECU. PREPARATION: Disconnect the connector "M5" of sliding roof ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the sliding roof ECU. NG: Go to next step.
2. Check the communication circuit inside driver door ECU. PREPARATION: Connect the connector "M5" of sliding roof ECU. Disconnect the connector "D24" of driver door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the driver door ECU. NG: Go to next step.
3. Check the communication circuit inside rear left door ECU. PREPARATION: Connect the connector "D24" of driver door ECU. Disconnect the connector "R12" of rear left door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the rear left door ECU. NG: w/ Driving position memory seat: Proceed to step 4 w/o Driving position memory seat: Proceed to step 5
4. Check the communication circuit inside power seat ECU. PREPARATION: Connect the connector "R12" of rear left door ECU. Disconnect the connector "P19" of power seat ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the power seat ECU. NG: Go to next step.
5. Check the communication circuit inside rear right door ECU. PREPARATION: w/ Driving position memory: Connect the connector "P19" of power seat ECU. w/o Driving position memory: Connect the connector "R12" of rear left door ECU. Disconnect the connector "R13" of rear right door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the rear right door ECU. NG: Go to next step.
6. Check the communication circuit inside passenger door ECU. PREPARATION: Connect the connector "R13" of rear right door ECU. Disconnect the connector "F11" of passenger door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Replace the passenger door ECU. NG: Go to next step.
7. Check for short circuit between passenger door ECU and rear right door ECU. PREPARATION: Disconnect the connector "R13" of rear right door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Repair or replace the wire harness between passenger door ECU and rear right door ECU. NG: w/ Driving position memory seat: Proceed to step 8 w/o Driving position memory seat: Proceed to step 9
8. Check for short circuit between rear right door ECU and power seat ECU. PREPARATION: Connect the connector "F11" of passenger door ECU. Disconnect the connector "P19" of power seat ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Repair or replace the wire harness between rear right door ECU and power seat ECU. NG: Go to next step.
9. Check for short circuit between power seat ECU and rear left door ECU(*1), rear right door ECU and rear left door ECU(*2). PREPARATION: w/ Driving position memory: Connect the connector "R13" of rear right door ECU. w/o Driving position memory: Connect the connector "F11" of passenger door ECU. Disconnect the connector "R12" of rear left door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Repair or replace the wire harness between seat ECU and rear left door ECU( 1 ), rear right door ECU and rear left door ECU( 2 ). w/ Driving position memory w/o Driving position memory NG: Go to next step.
10. Check for short circuit between rear left door ECU and driver door ECU. PREPARATION: w/ Driving position memory: Connect the connector "P19" of power seat ECU. w/o Driving position memory: Connect the connector "R13" of rear right door ECU. Disconnect the connector "D24" of driver door ECU. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Repair or replace the wire harness between rear left ECU and driver door ECU. NG: Go to next step.
11. Check for short circuit between driver door ECU and body ECU No. 2. PREPARATION: Connect the connector "R12" of rear left door ECU. Disconnect the connector of body ECU No. 2. HINT: Connector is disconnected by removing body ECU No. 2 from driver side junction block. CHECK: Check the DTC. OK: Code B1214/14 or B1215/15 is not output OK: Repair or replace the wire harness between driver door ECU and body ECU No. 2. NG: Go to next step.
12. Check for short circuit between passenger door ECU, sliding roof ECU and body ECU No. 1. PREPARATION: Connect the connector "D24" of driver door ECU. Install the body No.2 ECU to driver side junction block. Disconnect the connector "M5" of siding roof ECU and "F11" of passenger door ECU. Disconnect the connector of body ECU No. 1. HINT: Connector is disconnected by removing body ECU No. 1 from passenger side junction block. CHECK: Check wire harness between passenger door ECU, sliding roof ECU and body ECU No. 1. NG: Repair or replace the wire harness between passenger door ECU, sliding roof ECU and body ECU No. 1. OK: Replace the body ECU No. 1.

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Scheme 129

1. Check rear right door ECU. CHECK: Check if the rear right door window glass auto up. HINT: With this inspection rear right door ECU CPU can be diagnosed if it works normal or not. NG: Replace the rear right door ECU. OK: Go to next step.
2. Check wire harness. PREPARATION: Disconnect connector "F11" of passenger door ECU, "R13" of rear right door ECU and "P19" of power seat ECU. CHECK: Check continuity between terminals MPX1 of passenger door ECU and MPX2 of rear right door ECU. w/ Driving position memory seat: Check continuity between terminals MPX1 of rear right door ECU and MPX2 of power seat ECU. w/o Driving position memory seat: Check continuity between terminals MPX1 of rear right door ECU and MPX2 of rear left door ECU. OK: If there is OPEN in wire harness of either (a), (b) or (c), please repair it. There is a continuity in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the rear right door ECU.

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Scheme 130

1. Check rear left door ECU. CHECK: Check if the rear left door window glass auto up. HINT: With this inspection rear left door ECU CPU can be diagnosed if it works normal or not. NG: Replace the rear left door ECU. OK: Go to next step.
2. Check wire harness PREPARATION: ( ): w/o Driving position memory seat: Disconnect connector "D24" of driver door ECU, "R12" of rear left door ECU and "P19" of power seat ECU (or "R13" of rear right door ECU). CHECK: Check continuity between terminals MPX2 of driver door ECU and MPX1 of rear left door ECU. w/ Driving position memory seat: Check continuity between terminals MPX2 of rear left door ECU and MPX1 of power seat ECU. w/o Driving position memory seat: Check continuity between terminals MPX2 of rear left door ECU and MPX1 of rear right door ECU. OK: There is a continuity in wire harness of both (a) and (b) or (a) and (c), (a) or either (b) or (c). HINT: If there is OPEN in wire harness of either (a), (b) or (c), please repair it. NG: Repair or replace wire harness. OK: Replace the rear left door ECU.

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Scheme 131

1. Check Body ECU No. 2. CHECK: Check that the headlight comes on when operating the light control switch with the ignition switch off. HINT: With this inspection rear left door ECU CPU can be diagnosed if it works normal or not. NG: Replace the Body ECU No. 2. OK: Go to next step.
2. Check wire harness PREPARATION: Disconnect connector of Body ECU No. 2, "D24" of Driver door ECU and "C13" of Combination meter ECU. Remove the Body ECU No. 2 from Driver side junction block. CHECK: Check continuity between terminals MPX1 of Body ECU No. 2 and MPX1 of Driver door ECU. Check continuity between terminals MPX2 of Body ECU No. 2 and MPX- of Combination meter ECU. OK: There is a continuity in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the Body ECU No. 2.

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Scheme 132

1. Check ECM. CHECK: Check that the engine starts normally. HINT: With this inspection, ECM CPU can be diagnosed if it works normally or not. NG: Replace the ECM. OK: Go to next step.
2. Check wire harness. PREPARATION: Disconnect connector "B5" of body No.1 ECU, E5 of ECM, "A13" of A/C amplifier. CHECK: Check continuity between terminals MPX1 of body No.1 ECU and MPX1 of ECM. Check continuity between terminals MPX2 of ECM and MPX+ of A/C amplifier. OK: Continuity exists in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the ECM.

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Scheme 133

1. Check wire harness PREPARATION: Disconnect the connector "E5" of ECM, "G6" of gateway ECU, "C16" of steering pad switch, T5 of tilt and telescopic ECU and A/C amplifier. CHECK: Check continuity between terminals MPX+ of A/C amplifier and MPX2 of ECM. Check continuity between terminals MPD1, MPD2 of gateway ECU and MPX- of A/C amplifier. 3UZ-FE engine: Check continuity between terminals MPX1 of steering pad switch and MPX+ of A/C amplifier. Check continuity between MPX1 of tilt and telescopic ECU and MPX- of A/C amplifier. OK: Continuity exists in wire harness. NG: Repair or replace wire harness. OK: Replace the A/C amplifier.

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Scheme 134

1. Check combination meter ECU. CHECK: Start the engine and check that the speed meter and tachometer operate normally. HINT: With this inspection, the combination meter ECU CPU can be diagnosed if it works normally or not. NG: Replace the combination meter ECU. OK: Go to next step.
2. Check wire harness PREPARATION: Disconnect connector "B6" of body No.2 ECU, "C13" of combination meter ECU and "C8" of airbag sensor assembly. CHECK: Check continuity between terminals MPX2 of body No.2 ECU and MPX- of combination meter ECU. Check continuity between terminals MPX+ of combination meter ECU and MPX2 of airbag sensor assembly. OK: There is a continuity in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the combination meter ECU.

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Scheme 135

1. Check power seat ECU. CHECK: Check that the operation of front vertical and rear vertical is normal. HINT: With this inspection, the power seat ECU CPU can be diagnosed if it works normally or not. NG: Replace the power seat ECU. OK: Go to next step.
2. Check wire harness PREPARATION: Disconnect connector "R13" of rear right door ECU, "P19" of power seat ECU and "R12" of rear left door ECU. CHECK: Check continuity between terminals MPX1 of rear right door ECU and MPX2 of power seat ECU. Check continuity between terminals MPX1 of power seat ECU and MPX2 of rear left door ECU. OK: There is a continuity in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace power seat ECU.

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Scheme 136

1. Check sliding roof ECU. CHECK: Check that the operation of the sliding roof function is normal. HINT: With this inspection, the sliding roof ECU CPU can be diagnosed if it works normally or not. NG: Replace the sliding roof ECU. OK: Go to next step.
2. Check wire harness PREPARATION: Disconnect connector sliding roof ECU and Body ECU No. 1. HINT: Connected is disconnected by removing Body ECU No. 1 from passenger side junction block. CHECK: Check continuity between terminals MPX2 of Body ECU No. 1 and MPX1 of sliding roof ECU. OK: There is a continuity in wire harness. NG: Repair or replace wire harness. OK: Replace the sliding roof ECU.

See DTC B1266 / 66 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (+B SHORT), DTC B1267 / 67 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (GND SHORT)

Scheme 137

1. Check airbag sensor assembly. CHECK: Check whether or not DTC is output when changing to other airbag sensor assembly. OK: DTC must not be output. OK: Replace the airbag sensor assembly. (Original airbag sensor assembly is failure) NG: Go to next step.
2. Check wire harness. PREPARATION: Disconnect the connector "C8" of airbag sensor assembly, "C12" of combination meter ECU and "T5" of tilt and telescopic ECU. CHECK: Check continuity between terminals MPX1 of airbag sensor assembly and MPX2 of tilt and telescopic ECU. Check continuity between terminals MPX2 of airbag sensor assembly and MPX+ of combination meter ECU. OK: Continuity exists in wire harness of both (a) and (b), or either (a) or (b). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the airbag sensor assembly.

See DTC B1266 / 66 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (+B SHORT), DTC B1267 / 67 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (GND SHORT)

Scheme 138

1. Check steering pad switch. CHECK: Turn ignition switch ON and check that the steering pad switch operate normally. NG: Replace steering pad switch. OK: Go to next step.
2. Check wire harness. PREPARATION: Disconnect connector "G6" of gateway ECU "A13" of A/C amplifier ECU, "T5" of tilt and telescopic ECU and "C15" of steering pad switch. CHECK: Check continuity between terminals MPX1 of steering pad switch and MPD1, MPD2 of gateway ECU. Check continuity between terminals MPX1 of steering pad switch and MPX- of A/C amplifier. Check continuity between terminals MPX1 of steering pad switch and MPX1 of tilt and telescopic ECU. OK: There is a continuity in wire harness of both (a) and (b) or (a) and (c), or either (b) or (c). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the steering pad switch.

See DTC B1266 / 66 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (+B SHORT), DTC B1267 / 67 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (GND SHORT)

Scheme 139

1. Check gateway ECU. CHECK: Check that the operation of is normal. HINT: With this inspection, the gateway ECU CPU can be diagnosed if it works normally or not. NG: Replace the gateway ECU. OK: Go to next step.
2. Check wire harness. PREPARATION: Disconnect connector "T5" of tilt and telescopic ECU, "A13" of A/C amplifier ECU, steering pad switch and "G6" of gateway ECU. CHECK: Check continuity between terminals MPD1, MPD2 of gateway ECU and MPX- of A/C amplifier. Check continuity between terminals MPD1, MPD2 of gateway ECU and MPX1 of tilt and telescopic ECU. Check continuity between terminal MPD1, MPD2 of gateway ECU and MPX of steering pad switch. OK: There is a continuity in wire harness of both (a) and (b) or (a) and (c), or either (b) or (c). HINT: If there is OPEN in wire harness of either (a) or (b), please repair it. NG: Repair or replace wire harness. OK: Replace the gateway ECU.