Diagnosis Item 20: Diagnose when the M.U.T.-III cannot receive the data sent by 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>. <4WD>
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When servicing a CAN bus line, earth yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.
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FUNCTION
The diagnostic result demonstrates that "the M.U.T.-III cannot receive the sent data from the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>
- Malfunction of the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>
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STEP 1. Connector check: joint connector (CAN 3) and 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector
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The strand end of the twist wire should be within 10 cm from the connector.
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When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Repair the defective connector. Replace the joint connector as necessary.
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STEP 2. Resistance measurement at joint connector (CAN3) and 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector.
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A digital multimeter should be used.
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The test wiring harness should be used.
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(1)Disconnect joint connector (CAN3) and the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)
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When measuring the resistance, disconnect the negative battery terminal.
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Ensure that the negative battery terminal is disconnected.
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(4)Continuity between joint connector (CAN3) terminal No.5 and 4WD-ECU connector terminal No.5 <Vehicles without S-AWC> <LHD>
OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN3) terminal No.16 and 4WD-ECU connector terminal No.13 <Vehicles without S-AWC> <LHD>
OK: Continuity (2 Ω or less)
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(6)Continuity between joint connector (CAN3) terminal No.5 and AWC-ECU connector terminal No.23 <Vehicles with S-AWC> <LHD>
OK: Continuity (2 Ω or less)
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(7)Continuity between joint connector (CAN3) terminal No.16 and AWC-ECU connector terminal No.24 <Vehicles with S-AWC> <LHD>
OK: Continuity (2 Ω or less)
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(8)Continuity between joint connector (CAN3) terminal No.3 and 4WD-ECU connector terminal No.5 <Vehicles without S-AWC> <RHD>
OK: Continuity (2 Ω or less)
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(9)Continuity between joint connector (CAN3) terminal No.12 and 4WD-ECU connector terminal No.13 <Vehicles without S-AWC> <RHD>
OK: Continuity (2 Ω or less)
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(10)Continuity between joint connector (CAN3) terminal No.3 and AWC-ECU connector terminal No.23 <Vehicles with S-AWC> <RHD>
OK: Continuity (2 Ω or less)
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(11)Continuity between joint connector (CAN3) terminal No.12 and AWC-ECU connector terminal No.24 <Vehicles with S-AWC> <RHD>
OK: Continuity (2 Ω or less)
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Strictly observe the specified wiring harness repair procedure.
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Q.
Is the check result normal?
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<All the resistances measure 2 Ω or less> Go to Step 3.
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NO : <Either or all of the resistances measure more than 2 Ω> Repair intermediate connector C-23, or the wiring harness between joint connector (CAN3) and the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector.
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STEP 3. Resistance measurement at 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> connector.
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A digital multimeter should be used.
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(1)Remove the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>, and measure at the equipment side.
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(2)Resistance between 4WD-ECU connector terminal Nos.5 and 13 <Vehicles without S-AWC>
OK: 1 kΩ or more
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(3)Resistance between AWC-ECU connector terminal Nos.23 and 24 <Vehicles with S-AWC>
OK: 1 kΩ or more
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Q.
Is the check result normal?
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Power supply to the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC> may be suspected. Diagnose the electronic control 4WD or S-AWC. Refer to GROUP 27C - Troubleshooting <Electronic control 4WD> or GROUP 23C - Troubleshooting <S-AWC>.
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Replace the 4WD-ECU <Vehicles without S-AWC> or AWC-ECU <Vehicles with S-AWC>.
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