Body Multiplex Communication System - Diagnostics: Wiring Toyota Highlander I

Wiring Diagram

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check diagnostic trouble code (A ECU) . Check whether outputs of DTC will stop when the A ECU connector is disconnected. NOTE: Disconnect connectors in operational sequence, and start the next operation after the connector connected. NOTE: In this case, the A ECU represents power window regulator master switch assembly. Standard: Disconnected A ECU is abnormal when outputs of DTC stop . OK: Replace A ECU. NG: Go to next step.
2. Check diagnostic trouble code (B ECU) . Check whether outputs of DTC will stop when the B ECU connector is disconnected. NOTE: Disconnect connectors in operational sequence, and start the next operation after the connector is connected. NOTE: In this case, the B ECU represents sliding roof drive gear, combination meter assembly, air conditioning or theft warning ECU. Standard: Disconnected B ECU or wire harness between A ECU and B ECU is abnormal when outputs of DTC stop . OK: Go to next step. NG: Go to step 4 .
3. Check wire harness between A ECU and B ECU . Inspect short-circuit in +B or body ground. Check whether a DTC will be output when the A ECU connector is connected. NOTE: Disconnect connectors in operational sequence, and start the next operation after the connector connected. OK: Replace B ECU NG: Repair or replace between wire harness of A ECU and B ECU.
4. Check diagnostic trouble code (C ECU) Check whether outputs of DTC will stop when the A ECU connector is connected and the C ECU connector is disconnected. NOTE: Disconnect connectors in operational sequence, and start the next operation when the connector is connected. NOTE: In this case, the C ECU represents the ECM. Standard: Disconnected C ECU or wire harness between B ECU and C ECU is abnormal when outputs of diagnosis codes stop . OK: Go to next step. NG: Go to step 6 .
5. Check wire harness between B ECU and C ECU . Inspect short-circuit in +b or body ground. Check whether a DTC will be output when the B ECU connector is connected. NOTE: Disconnect connectors in operational sequence, and start the next operation after the connector connected. OK: Replace C ECU. NG: Repair or replace between wire harness of B ECU and C ECU.
6. Check wire harness MPX body ECU and A ECU or C ECU . Inspect short-circuit in +b or body ground. Disconnect connectors of the A ECU and the MPX body ECU. Inspect short-circuit in +B of wire harness between the A ECU and the MPX body ECU, and also in the body ground. Standard: 0 V when short-circuited in +B No continuity between each ECU and body ground when short-circuited in body ground NOTE: In this case, the A ECU represents the power window regulator master switch assembly. Inspect short-circuit in +B of wire harness between the C ECU and the MPX body ECU, and also in the body ground. Standard: 0 V when short-circuited in +B. No continuity between each ECU and body ground when short-circuited in body ground. NOTE: In this case, the C ECU represents the ECM. OK: Replace multiplex network body ECU. NG: Repair or replace between wire harness of MPX body ECU and A ECU or C ECU.

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check Continuity Of Communication Line Check the wire harness among meter assembly, ECM and MPX body ECU Disconnect connectors of the meter assembly, ECM and MPX body ECU. Inspect the continuity between terminals MPX1 of the ECM vehicle's side connector and MPX1 of the MPX body ECU vehicle's side connector. Standard: (Scheme 41)Inspect the continuity between terminals MPX2 of the ECM vehicle's side connector and MPX+ of the meter assembly vehicle's side connector. Standard: (Scheme 42)OK: Go to next step. NG: Repair or replace harness and connector.
2. Check ECM Inspect the ECM (power source input). NOTE: Do not disconnect the ECM connector. Inspection should be started from the backside of the connector. Standard: (Scheme 44)OK: Go to next step. NG: Repair or replace fuse or wire harness and connector.
3. Check ECM Inspect the ECM (body ground). NOTE: Do not disconnect the ECM connector. Inspection should be started from the backside of the connector. Inspect the continuity between each terminal of the ECM connector and the body ground. Standard: (Scheme 46)OK: Replace ECM. NG: Repair or replace harness and connector.

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check continuity of communication line . Inspect the wire harness among meter assembly and air conditioning and power window master switch. Disconnect connectors of the air conditioning amplifier, power window master switch and meter assembly. Inspect the continuity between terminal C11-9 (MPX-) of the air conditioning vehicle's side connector and terminal C11-9 (MPX-) of the meter assembly vehicle's side connector. Standard: Continuity Inspect the continuity between terminal A11-2 (MPX+) of the air conditioning vehicle's side connector and terminal 7 (MPX1) of the power window master switch. Standard: Continuity OK: Go to next step. NG: Repair or replace harness and connector.
2. Check air conditioner amplifier assy . Inspect the air conditioning (power source input). Disconnect the air conditioning amplifier connector A10. Inspect the voltage between terminal A10-12 (+B) of the vehicle's side connector and the body ground. Standard: 10-14 V OK: Go to next step. NG: Repair or replace fuse or wire harness and connector.
3. Check air conditioner amplifier assy . Inspect the air conditioning (body ground). Disconnect the air conditioning connector A10. Inspect the continuity between terminal A10-11 (GND) of the vehicle's side connector and the body ground. Standard: Continuity OK: Replace air conditioner amplifier assy. NG: Repair or replace harness and connector.

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check continuity of communication line . Check the wire harness among the power window master switch, theft warning ECU and air conditioning. Disconnect the connectors of the theft warning ECU, power window master switch and air conditioning amplifier. Check the continuity between terminal 10 (MPX1) of the theft warning ECU vehicle's side connector and terminal 7 (MPX1) of the power window master switch vehicle's side connector. Check the continuity between terminal 10 (MPX1) of the theft warning ECU vehicle's side connector and terminal A11-2 (MPX+) of the air conditioning vehicle's side connector. Standard: Continuity OK: Go to next step. NG: Repair or replace harness and connector.
2. Check theft warning ECU assy Inspect the theft warning ECU (power source input). Disconnect the theft warning ECU connector. Check the voltage between terminal 2 (+B1) of the theft warning ECU and the body ground. Standard: 10 - 14 V OK: Go to next step. NG: Repair or replace fuse or wire harness and connector.
3. Check theft warning ECU assy Inspect the theft warning ECU (body ground). Disconnect the theft warning ECU connector. Check the continuity between terminal 11 (E) of the theft warning ECU vehicle's side connector and the body ground. Standard: Continuity OK: Replace theft warning ECU assy. NG: Repair or replace harness and connector.

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check continuity of communication line. Inspect the wire harness among ECM and meter assembly and air conditioning. Disconnect the connectors of the meter assembly, ECM and air conditioning. Inspect the continuity between terminal MPX+ of the meter assembly vehicle's side connector and terminal MPX2 of the ECM vehicle's side connector. Standard: (Scheme 57)Inspect the continuity between terminal C11-21 (MPX-) of the meter assembly vehicle's side connector and terminal C11-2 (MPX-) of the air conditioning amplifier vehicle's side connector. Standard: Continuity OK: Go to next step. NG: Repair or replace harness and connector.
2. Check combination meter assy. Inspect the meter assembly (power source input). Disconnect the meter assembly connector C11. Inspect the voltage of each terminal of the vehicle's side connector. Standard: (Scheme 59)NOTE: If the value is not as specified, there may be a malfunction in the vehicle's side connector. OK: Go to next step. NG: Repair or replace fuse or wire harness and connector.
3. Check combination meter assy. Inspect the meter assembly (body ground). Disconnect the meter assembly connector C11. Inspect the continuity between terminal C11-2 (E2) of the vehicle's side connector and the body ground. Standard: Continuity OK: Replace combination meter assy. NG: Repair or replace harness and connector.

Note. For complete multiplex system wiring diagram, see COMPUTER DATA LINES .

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1. Check continuity of communication line. Inspect the wire harness among ECM and sliding roof drive gear and meter assembly. Disconnect the connectors of the sliding roof drive gear, ECM and meter assembly. Inspect the continuity between terminal MPX1 of the sliding roof drive gear vehicle's side connector and terminal MPX2 of the ECM vehicle's side connector. Standard: (Scheme 63)Inspect the continuity between terminal 2 (MPX1) of the sliding roof drive gear vehicle's side connector and terminal C12-9 (MPX+) of the meter assembly vehicle's side connector. Standard: Continuity OK: Go to next step. NG: Repair or replace harness and connector.
2. Check sliding roof drive gear sub-assy. Inspect the sliding roof drive gear. Disconnect the sliding roof drive gear connector. Inspect the voltage of each terminal of the vehicle's side connector. Standard: OK: Go to next step. NG: Repair or replace fuse or wire harness and connector.
3. Check sliding roof drive gear sub-assy. Inspect the sliding roof drive gear. Disconnect the sliding roof drive gear connector. Inspect the voltage of each terminal of the vehicle's side connector. Standard: (Scheme 67) OK: Replace sliding roof drive gear sub-assy. NG: Repair or replace harness and connector.