Diagnosis Item
7: Diagnose when the M.U.T.-III cannot receive the data sent by SRS-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 SRS-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot
receive the SRS-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from SRS-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the SRS-ECU
- Malfunction of the SRS-ECU
DIAGNOSIS PROCEDURE
STEP 1. Connector check: joint connector (CAN1) and SRS-ECU
connector.
caution |
The strand end of the twist wire should be within 10 cm from
the connector. For details refer to service precautions.
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When checking the joint connector, ensure that its wiring harness side and its short pins
are not damaged.
Q.
Is the check result normal?
Go to Step 2.
Repair the defective connector. Replace the joint connector as necessary.
STEP 2. Resistance measurement at joint connector (CAN1) and SRS-ECU
connector.
caution |
- A digital multimeter should be used. For details
refer to service precautions.
- The test wiring harness should be used. For details refer to service precautions.
- Strictly observe the specified wiring harness repair procedure. For details refer
to service precautions.
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(1)Disconnect joint connector (CAN1) and the SRS-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. For details refer to service precautions.
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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 SRS-ECU connector
terminal No. 33. OK: Continuity (2 Ω
or less)
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(5)Continuity between joint connector (CAN1) terminal No. 15 and SRS-ECU connector terminal
No. 34. OK: Continuity (2 Ω
or less)
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Q.
Is the check result normal?
<All the resistances measure 2 Ω
or less>
Power supply
to the SRS-ECU may be suspected. Diagnose the SRS. Refer to GROUP 52B -
Troubleshooting
.
NO : <Either or all of the resistances measure more than 2 Ω>
Repair
the wiring harness between joint connector (CAN1) and the SRS-ECU connector.