Diagnosis Item 9: Diagnose when the M.U.T.-III cannot receive the data sent by ETACS-ECU. <Vehicles for LHD>
caution |
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 ETACS-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the ETACS-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from ETACS-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the ETACS-ECU
- Malfunction of the ETACS-ECU
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STEP 1. Connector check: joint connector (CAN1), joint connector (CAN2) and ETACS-ECU connector
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caution |
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 joint connector (CAN2).
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caution |
A digital multimeter should be used.
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caution |
The test wiring harness should be used.
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(1)Disconnect joint connector (CAN1) and the joint connector (CAN2), 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.9 and joint connector (CAN2) terminal No.7. OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN1) terminal No.20 and joint connector (CAN2) terminal No.18. OK: Continuity (2 Ω or less)
caution |
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 (CAN1) and the joint connector (CAN2).
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STEP 3. Resistance measurement at joint connector (CAN2) and ETACS-ECU connector.
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caution |
A digital multimeter should be used.
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caution |
The test wiring harness should be used.
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(1)Disconnect joint connector (CAN2) and the ETACS-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)
caution |
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 (CAN2) terminal No.11 and ETACS-ECU connector terminal No.56. OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN2) terminal No.22 and ETACS-ECU connector terminal No.65. OK: Continuity (2 Ω or less)
caution |
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 4
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NO : <Either or all of the resistances measure more than 2 Ω> Repair the wiring harness between joint connector (CAN2) and the ETACS-ECU connector.
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STEP 4. Resistance measurement at ETACS-ECU connector.
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caution |
A digital multimeter should be used.
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(1)Remove the ETACS-ECU, and measure at the equipment side.
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(2)Resistance at ETACS-ECU connector terminal Nos.56 and 65 OK: 120 ± 20 Ω
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Q.
Is the check result normal?
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<Within 120 ± 20 Ω> Power supply to the ETACS-ECU may be suspected (Refer to GROUP 54A - ETACS, Troubleshooting).
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<Not within 120 ± 20 Ω> Replace the ETACS-ECU (Refer to GROUP 54A - ETACS, ETACS-ECU).
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