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Diagnostic Item 31: Diagnose when the scan tool cannot receive the data sent by BSW-ECU. <Vehicles with Blind Spot Warning [BSW] (with Lane Change Assist) system>
 
 
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.-IIISE) cannot receive the sent data from the BSW-ECU" when the scan tool (M.U.T.-IIISE) checks the periodically sent data from each ECU and cannot receive the BSW-ECU data only.
 
 
TROUBLE JUDGMENT CONDITIONS
Scan tool (M.U.T.-IIISE) judges the trouble when the periodically sent data from BSW-ECU cannot be received.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Power supply circuit malfunction of the BSW-ECU
  • Malfunction of the BSW-ECU (master)
  • Malfunction of the gateway-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: gateway-ECU connector and BSW-ECU (master) connector.
cautionThe strand end of the twist wire should be within 10 cm (4 inches) from the connector. For details refer to .
Is the check result normal?
Go to Step 2.
Repair the defective connector. Replace the connector as necessary.
 
STEP 2. Resistance measurement at gateway-ECU connector and BSW-ECU (master) connector.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect the gateway-ECU connector and the BSW-ECU (master) connector, and measure at the wiring harness side.
(2) Turn off the power supply mode of the electric motor switch.
(3)
cautionWhen measuring the resistance, disconnect the negative 12V starter battery terminal. For details refer to .
Ensure that the negative 12V starter battery terminal is disconnected.
(4) Continuity between gateway-ECU connector terminal No.6 and BSW-ECU (master) connector terminal No.4
OK: Continuity (2 ohms or less)
(5) Continuity between gateway-ECU connector terminal No.5 and BSW-ECU (master) connector terminal No.9
OK: Continuity (2 ohms or less)
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 intermediate connectors, or wiring harness between gateway-ECU connector and the BSW-ECU (master) connector.
 
STEP 3. Resistance measurement at gateway-ECU connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the gateway-ECU, and measure at the equipment side.
(2) Resistance at gateway-ECU connector terminal Nos.6 and 5
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 4.
<Not within 120 ± 20 ohms> Replace the gateway-ECU.
 
STEP 4. Resistance measurement at BSW-ECU (master) connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the BSW-ECU (master), and measure at the equipment side.
(2) Resistance at BSW-ECU (master) connector terminal Nos.4 and 9
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
<Not within 120 ± 20 ohms> Replace the BSW-ECU (master).