Diagnosis Item 23: Diagnose when the M.U.T.-III cannot receive the data sent by ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC>.
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 ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC>" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC>
- Malfunction of the hydraulic unit (ABS-ECU) <Vehicles without ASC> or hydraulic unit (ASC-ECU) <Vehicles with ASC>
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STEP 1. Connector check: joint connector (CAN1) and ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> 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 ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> connector.
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caution |
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 ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> 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.7 and ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> connector terminal No.11 OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN1) terminal No.16 and ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> connector terminal No.10 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 ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> connector.
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STEP 3. Resistance measurement at ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> connector.
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caution |
A digital multimeter should be used.
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(1)Remove the ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC>, and measure at the equipment side.
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(2)Resistance between ABS-ECU <vehicles without ASC> or ASC-ECU <vehicles with ASC> connector terminal Nos.11 and 10 OK: 1 kΩ or more
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Q.
Is the check result normal?
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Power supply to the ABS-ECU <Vehicles without ASC> or ASC-ECU <Vehicles with ASC> may be suspected. Diagnose the ABS system <Vehicles without ASC> or ASC system <Vehicles with ASC>. Refer to GROUP 35B - Troubleshooting <Vehicles without ASC> or GROUP 35C - Troubleshooting <Vehicles with ASC>.
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Replace the hydraulic unit (ABS-ECU) <Vehicles without ASC> or hydraulic unit (ASC-ECU) <Vehicles with ASC>.
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