INSPECTION PROCEDURE
2: Power supply circuit system
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To SRS-ECU, the power is supplied
from two independent circuits (fuse No. 15 and 21) via
ignition switch (IG1) <vehicles without keyless
operation system> or IG1 relay <Vehicles
with keyless operation system>.
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If the power is not supplied to
SRS-ECU, the communication between M.U.T.-III and SRS-ECU
cannot be established.
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- Damaged wiring harness and connectors
- Battery failure
- Malfunction of the charging system
- Malfunction of SRS-ECU
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STEP 1. Fuse Nos. 15, 21 check.
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Q.
Is the fuse in good condition?
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Go to Step
3.
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Go to Step
2
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STEP 2. Fuse open circuit check
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(2)Turn the ignition switch to the "ON" position,
wait for at least one minute, and
then turn the switch OFF.
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Q.
Is the fuse in good condition?
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Go to Step
3.
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Repair the wiring
harness IG1A line between the junction block connector and
SRS-ECU
connector, IG1B line between the junction block connector
terminal No. 8 and the SRS-ECU connector,
and replace the fuse.
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STEP 3. Resistance measurement at the SRS-ECU
connector.
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![](../../../img/52/AC905015AC00ENG.png)
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(1)While pushing the part "A"
indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the
lock lever, and disconnect the SRS-ECU
connectors. (2)Take the measurements below at the wiring
harness side connectors.
- Continuity GND1 line between wiring harness side
connector
and body earth
OK: Continuity (less than 2
Ω)
Q.
Is the check result normal?
Go to Step
4.
Repair
the wiring harness GND1 line between the SRS-ECU connector
and the body
earth.
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STEP 4. Voltage measurement at the SRS-ECU connector
(IG1A, IG1B line).
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(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
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![](../../../img/52/AC905015AC00ENG.png)
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(2)While pushing the part "A"
indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the
lock lever, and disconnect the SRS-ECU
connector. (3)Connect the negative battery
terminal. (4)Ignition switch: ON (5)Take the
measurements below at the harness side connector.
- Voltage IG1A, IG1B line between the SRS-ECU
connector
and the body earth
OK: 9 V or more (6)Disconnect the
negative battery terminal.
Q.
Is the check result normal?
Go to Step
6.
Go to Step
5.
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STEP 5. Resistance measurement at the SRS-ECU connector
(IG1A, IG1B
line).
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(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
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![](../../../img/52/AC905015AC00ENG.png)
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(2)While pushing the part "A"
indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the
lock lever, and disconnect the SRS-ECU
connector. (3)
- Continuity IG1A line between junction block
connector and
SRS-ECU connector
- Continuity IG1B line between junction block
connector and SRS-ECU connector
OK: Continuity (less than 2
Ω)
Q.
Is the check result normal?
Go to Step
6.
Repair
the wiring harness IG1A line between the junction block
connector and the
SRS-ECU connector, IG1B line between the junction block
connector and SRS-ECU connector.
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STEP 6. Trouble symptom check.
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Q.
Is the communication between M.U.T.-III and SRS-ECU
possible?
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Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunction ).
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Replace SRS-ECU
(Refer to ).
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