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Diagnostic Item 15: Diagnose when the scan tool cannot receive the data sent by SRS-ECU
 
 
cautionWhen servicing a CAN bus line, ground 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.
 
 
FUNCTION
The diagnostic result demonstrates that "the scan tool (M.U.T.-III) cannot receive the sent data from the SRS-ECU" when the scan tool (M.U.T.-III) checks the periodically sent data from each ECU and cannot receive the SRS-ECU data only.
 
 
TROUBLE JUDGMENT CONDITIONS
Scan tool (M.U.T.-III) judges the trouble when the periodically sent data from SRS-ECU cannot be received.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Power supply circuit malfunction of the SRS-ECU
  • Malfunction of the SRS-ECU
 
 
DIAGNOSIS
STEP 1. Connector check: joint connector (CAN3) and SRS-ECU connector
cautionThe strand end of the twist wire should be within 10 cm from the connector. For details refer to .
When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.
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 (CAN3) and SRS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect joint connector (CAN3) and the SRS-ECU connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the LOCK (OFF) position.
(3)
cautionWhen measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.
(4) Continuity between joint connector (CAN3) terminal No.8 and SRS-ECU connector terminal No.30
OK: Continuity (2 ohms or less)
(5) Continuity between joint connector (CAN3) terminal No.19 and SRS-ECU connector terminal No.29
OK: Continuity (2 ohms or less)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
Is the check result normal?
<All the resistances measure 2 ohms or less> Go to Step 3.
: <Either or all of the resistances measure more than 2 ohms> Repair the wiring harness between joint connector (CAN3) and the SRS-ECU connector.
 
STEP 3. Resistance measurement at SRS-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the SRS-ECU, and measure at the equipment side.
(2) Resistance between SRS-ECU connector terminal Nos.30 and 29
OK: 1 kΩ or more
Is the check result normal?
Power supply to the SRS-ECU may be suspected. Diagnose the SRS. Refer to GROUP 52B - Troubleshooting .
Replace the SRS-ECU.