Diagnosis Item 17: Diagnose when the M.U.T.-III cannot receive the data sent by clearance warning control unit. <Vehicles with ultrasonic misacceleration mitigation system/corner sensor system or reversing sensor system>
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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 clearance warning control unit" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the clearance warning control unit data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from clearance warning control unit cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the clearance warning control unit
- Malfunction of the clearance warning control unit
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STEP 1. Connector check: joint connector (CAN3) <LHD> or joint connector (CAN4) <RHD> and clearance warning control unit 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) <LHD> or joint connector (CAN4) <RHD> and clearance warning control unit 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) <LHD> or joint connector (CAN4) <RHD> and the clearance warning control unit 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.3 and clearance warning control unit connector terminal No.4 <LHD>
OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN3) terminal No.14 and clearance warning control unit connector terminal No.3 <LHD>
OK: Continuity (2 Ω or less)
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(6)Continuity between joint connector (CAN4) terminal No.2 and clearance warning control unit connector terminal No.4 <RHD>
OK: Continuity (2 Ω or less)
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(7)Continuity between joint connector (CAN4) terminal No.11 and clearance warning control unit connector terminal No.3 <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 the wiring harness between joint connector (CAN3) <LHD> or joint connector (CAN4) <RHD> and the clearance warning control unit connector.
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STEP 3. Resistance measurement at clearance warning control unit connector.
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A digital multimeter should be used.
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(1)Remove the clearance warning control unit, and measure at the equipment side.
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(2)Resistance between clearance warning control unit connector terminal Nos.4 and 3
OK: 1 kΩ or more
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Q.
Is the check result normal?
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Power supply to the clearance warning control unit may be suspected. Diagnose the clearance warning control unit. Refer to GROUP 54A - Troubleshooting  <Vehicles with ultrasonic misacceleration mitigation system/corner sensor system> or <Vehicles with reversing sensor system>.
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Replace the clearance warning control unit.
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