Diagnosis Item 30: Diagnose when the M.U.T.-III cannot receive the data sent by BSW-ECU. <Vehicles with Blind Spot Warning [BSW] (with Lane Change Assist) system>
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When servicing a CAN bus line, earth 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.
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FUNCTION
The diagnostic result demonstrates that "the M.U.T.-III cannot receive the sent data from the BSW-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the BSW-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from BSW-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the BSW-ECU
- Malfunction of the BSW-ECU (master)
- Malfunction of the gateway-ECU
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STEP 1. Connector check: gateway-ECU connector and BSW-ECU (master) connector.
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The strand end of the twist wire should be within 10 cm from the connector.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Repair the defective connector. Replace the connector as necessary.
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STEP 2. Resistance measurement at gateway-ECU connector and BSW-ECU (master) connector.
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A digital multimeter should be used.
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The test wiring harness should be used.
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(1)Disconnect the gateway-ECU connector and the BSW-ECU (master) connector, and measure at the wiring harness side.
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(2)Turn off the power supply mode of the electric motor switch.
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(3)
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When measuring the resistance, disconnect the negative auxiliary battery terminal.
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Ensure that the negative auxiliary battery terminal is disconnected.
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(4)Continuity between gateway-ECU connector terminal No.6 and BSW-ECU (master) connector terminal No.4
OK: Continuity (2 Ω or less)
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(5)Continuity between gateway-ECU connector terminal No.5 and BSW-ECU (master) connector terminal No.9
OK: Continuity (2 Ω or less)
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Q.
Is the check result normal?
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<All the resistances measure 2 Ω or less> Go to Step 3.
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NO : <Either or all of the resistances measure more than 2 Ω> Repair the intermediate connectors C-25 and G36, or wiring harness between gateway-ECU connector and the BSW-ECU (master) connector.
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STEP 3. Resistance measurement at gateway-ECU connector.
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A digital multimeter should be used.
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(1)Remove the gateway-ECU, and measure at the equipment side.
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(2)Resistance at gateway-ECU connector terminal Nos.2 and 3
OK: 120 ± 20 Ω
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Q.
Is the check result normal?
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<Within 120 ± 20 Ω> Go to Step 4.
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<Not within 120 ± 20 Ω> Replace the gateway-ECU.
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STEP 4. Resistance measurement at BSW-ECU (master) connector.
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A digital multimeter should be used.
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(1)Remove the BSW-ECU (master), and measure at the equipment side.
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(2)Resistance at BSW-ECU (master) connector terminal Nos.6 and 5
OK: 120 ± 20 Ω
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Q.
Is the check result normal?
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<Within 120 ± 20 Ω> The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
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<Not within 120 ± 20 Ω> Replace the BSW-ECU (master).
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