Inspection Procedure 2: Power supply circuit system
OPERATION
- The SRS-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 40 and the SRS-ECU terminal 2 and multi-purpose fuse 37 and the SRS-ECU terminal 27.
- If the power supply to the SRS-ECU has failed, M.U.T.-III will not be able to communicate with it.
PROBABLE CAUSES
- Damaged wiring harness or connector
- Charging system failed
- Malfunction of the SRS-ECU
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STEP 1. Check junction block fuse number 40 or 37.
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Q.
Is the fuse in good condition?
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 Go to Step 3.
 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 ignition switch to the "LOCK" (OFF) position.
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Q.
Is the fuse in good condition?
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Go to Step 5.
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Repair the wiring harness between junction block connector B-231 (terminal No.13, 31) and SRS-ECU connector B-109 (terminal No.27, 2), and replace the fuse.
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STEP 3. Resistance measurement at SRS-ECU connector B-109.
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(1)Disconnect the negative battery terminal.
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(2)Disconnect the connector B-109.
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(3)Check for continuity between B-109 harness side connector terminals 4 and body earth.
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Then go to Step 4.
Repair the wiring harness between SRS-ECU connector B-109 terminals 4 and the body earth.
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STEP 4. Voltage measurement at the SRS-ECU connector B-109.
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(1)Disconnect the negative battery terminal.
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(2)Disconnect SRS-ECU connector B-109.
(3)Connect the negative battery terminal.
(4)Turn the ignition switch to the "ON" position.
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(5)Voltage measurement between B-109 harness side connector (terminal 2 or 27) and body earth.
OK: 9 V or more
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness between SRS-ECU connector B-109 (terminal No.2, 27) and ignition switch (IG1).
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STEP 5. Retest the system.
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Q.
Can the SRS-ECU communicate with the M.U.T.-III?
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It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Cope with Intermittent Malfunction  .
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Replace the SRS-ECU (Refer to ).
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