Diagnosis Item 8: Diagnose when the M.U.T.-III cannot receive the data sent by transfer-ECU.
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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 transfer-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the transfer-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from transfer-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the transfer-ECU
- Malfunction of the transfer-ECU
DIAGNOSIS PROCEDURE
STEP 1. Connector check: joint connector (CAN1) <LHD>, joint connector (CAN2) <RHD> and transfer-ECU connector
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The strand end of the twist wire should be within 10 cm from the connector. For details refer to  .
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When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.
Q.
Is the check result normal?
Go to Step 2.
Repair the defective connector. Replace the joint connector as necessary.
STEP 2. Resistance measurement at joint connector (CAN1) <LHD>, joint connector (CAN2) <RHD> and transfer-ECU connector.
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A digital multimeter should be used. For details refer to .
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The test wiring harness should be used. For details refer to .
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(1)Disconnect joint connector (CAN1) <LHD>, joint connector (CAN2) <RHD> and the transfer-ECU 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. For details refer to .
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Ensure that the negative battery terminal is disconnected.
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(4)Continuity between joint connector (CAN1) terminal No.4 and transfer-ECU connector terminal No.56 <LHD>
OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN1) terminal No.15 and transfer-ECU connector terminal No.55 <LHD>
OK: Continuity (2 Ω or less)
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(6)Continuity between joint connector (CAN2) terminal No.4 and transfer-ECU connector terminal No.56 <RHD>
OK: Continuity (2 Ω or less)
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(7)Continuity between joint connector (CAN2) terminal No.15 and transfer-ECU connector terminal No.55 <RHD>
OK: Continuity (2 Ω or less)
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Strictly observe the specified wiring harness repair procedure. For details refer to .
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Q.
Is the check result normal?
<All the resistances measure 2 Ω or less> Power supply to the transfer-ECU may be suspected. Diagnose the ES4/SS4 (Refer to GROUP 22A - Troubleshooting ).
NO : <Either or all of the resistances measure more than 2 Ω> Repair the wiring harness between joint connector (CAN1) <LHD>, joint connector (CAN2) <RHD> and the transfer-ECU connector.