INSPECTION PROCEDURE
2: Power supply circuit system
OPERATION
To SRS-ECU, the power is supplied from two
independent circuits (fuse No. 2) via IG1 relay
of ETACS-ECU.
If the power is not supplied to SRS-ECU, the
communication between M.U.T.-III and SRS-ECU cannot
be established.
PROBABLE CAUSES
- Damaged wiring harness and connectors
- Battery failure
- Malfunction of the charging system
- Malfunction of SRS-ECU
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STEP 1. Fuse Nos. 2 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 ETACS-ECU connector 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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(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
connector.
(2)Take the measurements below at the SRS-ECU
wiring harness side connectors.
- Continuity GND2 line between SRS-ECU 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 GND2 line between the SRS-ECU connector
and the earth.
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STEP 4. Voltage measurement at the SRS-ECU
connector.
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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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(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 SRS-ECU harness side connector.
- Voltage between IG1A line and 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.
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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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(2)Disconnect the ETACS-ECU connector.
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(3)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.
(4)
- Continuity IG1A line between ETACS-ECU connector and
SRS-ECU connector
OK: Continuity (less than 2
Ω)
Q.
Is the check result normal?
Replace the
ETACS-ECU (Refer to GROUP 54A - ETACS-ECU  ).
Repair the wiring
harness IG1A line between the ETACS-ECU connector and the
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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