Diagnosis Item
17: Diagnose when the M.U.T.-III cannot receive the data sent by ASC-ECU.
| 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 ASC-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive
the ASC-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from ASC-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the ASC-ECU
- Malfunction of the ASC-ECU
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STEP 1. Connector check: joint connector (CAN2) and ASC-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 (CAN2) and ASC-ECU
connector.
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| caution |
- A digital multimeter should
be used.
- The test wiring harness should be used.
- Strictly observe the specified wiring harness repair procedure.
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(1)Disconnect joint connector (CAN2) and the hydraulic unit assembly (integrated with
ASC-ECU), 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 (CAN2) terminal No.9 and hydraulic unit assembly
(integrated with ASC-ECU connector terminal No.26.
OK: Continuity (2 Ω or less)
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(5)Continuity between joint connector (CAN2) terminal No.20 and hydraulic unit assembly
(integrated with ASC-ECU connector terminal No.14.
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> Power supply
to the hydraulic unit assembly (integrated with ASC-ECU) may be suspected. Diagnose the ASC-ECU.
Refer to GROUP 35C - Troubleshooting, Inspection Procedure 11  .
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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 hydraulic unit assembly (integrated
with ASC-ECU) connector.
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