Inspection Procedure 1: Power Supply Circuit Check
COMMENTS ON TROUBLE SYMPTOM
If the gateway-ECU functions do not work at all, power supply to the gateway-ECU, or the gateway-ECU itself may have a problem.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Malfunction of gateway-ECU
DIAGNOSIS PROCEDURE
STEP 1. Voltage measurement at the gateway-ECU connector
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(1)Disconnect the 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)Measure the voltage between the gateway-ECU connector (+B terminal) and the body earth.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 3.
Go to Step 2.
STEP 2. Check of open circuit in +B line between the fusible link and gateway-ECU connector.
Q.
Is the check result normal?
Perform the battery test (Refer to GROUP 54A - Battery - Battery Test 
) or check the battery terminals for looseness or contamination.
Repair the connector(s) or wiring harness.
STEP 3. Voltage measurement at the gateway-ECU connector
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the "ON" position.
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(3)Measure the voltage between the gateway-ECU connector (IG terminal) and the body earth.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 6.
Go to Step 4.
STEP 4. M.U.T.-III other system service data
Check the input signal from the ignition switch (IG1) in the ETACS-ECU.
- Turn the ignition switch to the "ON" position.
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Item No.
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Item name
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Normal condition
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30
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IG SW (IG1)
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ON
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OK: Normal condition is displayed.
Q.
Is the check result normal?
Go to Step 5.
NO : Troubleshoot the ETACS-ECU (Refer to Inspection Procedure 2 "The ignition switch (IG1) signal is not received." ).
STEP 5. Check of open circuit in IG line between the ignition switch (IG1) and gateway-ECU connector.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.
STEP 6. Resistance measurement at the gateway-ECU connector
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Measure the resistance between the gateway-ECU connector (GND terminal) and the body earth.
OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
Go to Step 8.
Go to Step 7.
STEP 7. Check of open circuit in GND line between gateway-ECU connector and body earth.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.
STEP 8. Retest the system
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the gateway-ECU (Refer to ).