Diagnosis Item 26: Diagnose when the M.U.T.-III cannot receive the data sent by CVT-ECU <CVT> or A/T-ECU <A/T>.
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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 CVT-ECU <CVT> or A/T-ECU <A/T>" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the CVT-ECU <CVT> or A/T-ECU <A/T> data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from CVT-ECU <CVT> or A/T-ECU <A/T> cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the CVT-ECU <CVT> or A/T-ECU <A/T>
- Malfunction of the CVT-ECU <CVT> or A/T-ECU <A/T>
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STEP 1. Connector check: joint connector (CAN1) and CVT-ECU <CVT> or A/T-ECU <A/T> 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 (CAN1) and CVT-ECU <CVT> or A/T-ECU <A/T> 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 (CAN1) and the CVT-ECU <CVT> or A/T-ECU <A/T> 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 (CAN1) terminal No.4 and CVT-ECU connector terminal No.9 <CVT>
OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN1) terminal No.13 and CVT-ECU connector terminal No.10 <CVT>
OK: Continuity (2 Ω or less)
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(6)Continuity between joint connector (CAN1) terminal No.4 and A/T-ECU connector terminal No.10 <A/T>
OK: Continuity (2 Ω or less)
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(7)Continuity between joint connector (CAN1) terminal No.13 and A/T-ECU connector terminal No.11 <A/T>
OK: Continuity (2 Ω or less)
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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 the wiring harness between joint connector (CAN1) and the A/T-ECU <A/T> or CVT-ECU <CVT> connector.
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STEP 3. Resistance measurement at A/T-ECU <A/T> or CVT-ECU <CVT> connector.
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A digital multimeter should be used.
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(1)Remove the A/T-ECU <A/T> or CVT-ECU <CVT>, and measure at the equipment side.
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(2)Resistance between A/T-ECU connector terminal Nos.11 and 10 <A/T>
OK: 1 kΩ or more
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(3)Resistance between CVT-ECU connector terminal Nos.9 and 10 <CVT>
OK: 1 kΩ or more
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Q.
Is the check result normal?
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Power supply to the A/T-ECU <A/T> or CVT-ECU <CVT> may be suspected. Diagnose the A/T system <A/T> or CVT system <CVT>. Refer to GROUP 23C - Troubleshooting <A/T> or GROUP 23A - Troubleshooting <CVT>.
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Replace the A/T-ECU <A/T> or CVT-ECU <CVT>.
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