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DIAGNOSTIC ITEM 18: Communication with BSW-ECU is not possible [CAN-C (BSW)] <Vehicles BSW (with LCA)/RCTA function>
 
 
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 gateway-ECU receives data from the BSW-ECU (master) via CAN-C (BSW) line.
 
 
TROUBLE JUDGEMENT CONDITIONS
Scan tool MB991958 judges the trouble when the data from the BSW-ECU (master) cannot be received.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Malfunction of the BSW-ECU (master) power supply circuit
  • 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 C-49 and BSW-ECU (master) connector G-25
cautionThe strand end of the twist wire should be within 10 cm from the connector.
Is the check result normal?
Go to Step 2.
Repair the defective connector.
 
STEP 2. Continuity check between gateway-ECU connector C-49 and BSW-ECU (master) connector G-25
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Check the continuity between gateway-ECU connector C-49 terminal No. 19 and BSW-ECU (master) connector G-25 terminal No. 4. <CAN_H>
OK: Continuity (2 ohms or less)
(5) Check the continuity between gateway-ECU connector C-49 terminal No. 18 and BSW-ECU (master) connector G-25 terminal No. 9. <CAN_L>
OK: Continuity (2 ohms or less)
Is the check result normal?
Go to Step 3.
Repair the intermediate connectors C-27 and G-20, or wiring harness between the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25.
 
STEP 3. Resistance measurement at gateway-ECU connector C-49 (short to ground check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Measure the resistance between gateway-ECU connector C-49 terminal No. 19 and body ground. <CAN_H>
OK: 1 kΩ or more
(5) Measure the resistance between gateway-ECU connector C-49 terminal No. 18 and body ground. <CAN_L>
OK: 1 kΩ or more
Is the check result normal?
Go to Step 4.
Repair the intermediate connectors C-27 and G-20, or wiring harness between the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25.
 
STEP 4. Voltage measurement at gateway-ECU connector C-49 (short to power supply check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25 and measure at the wiring harness side.
(2) Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3) Measure the voltage between gateway-ECU connector C-49 terminal No. 19 and body ground. <CAN_H>
OK: 1.0 volt or less
(4) Measure the voltage between gateway-ECU connector C-49 terminal No. 18 and body ground. <CAN_L>
OK: 1.0 volt or less
Is the check result normal?
Go to Step 5.
Repair the intermediate connectors C-27 and G-20, or wiring harness between the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25.
 
STEP 5. Resistance measurement at gateway-ECU connector C-49 (line-to-line short check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Measure the resistance between gateway-ECU connector C-49 terminal Nos. 18 and 19.
OK: 1 kΩ or more
Is the check result normal?
Go to Step 6.
Repair the intermediate connectors C-27 and G-20, or wiring harness between the gateway-ECU connector C-49 and BSW-ECU (master) connector G-25.
 
STEP 6. Resistance measurement at gateway-ECU connector C-49
cautionA digital multimeter should be used. For details refer to .
(1) Remove the gateway-ECU, and measure at the equipment side.
(2) Measure the resistance between gateway-ECU connector C-49 terminal Nos. 18 and 19.
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 7.
<Not within 120 ± 20 ohms> Replace the gateway-ECU (Refer to ).
 
STEP 7. Resistance measurement at BSW-ECU (master) connector G-25
cautionA digital multimeter should be used. For details refer to .
(1) Remove the BSW-ECU, and measure at the equipment side.
(2) Measure the resistance between BSW-ECU (master) connector G-25 terminal Nos. 4 and 9.
OK: 120 ± 20 ohms
Is the check result normal?
<Within 120 ± 20 ohms> Power supply to the BSW-ECU (master) may be suspected (Refer to GROUP 54A - Blind Spot Warning [BSW] (with Lane Change Assist)/Rear Cross Traffic Alert (RCTA), Troubleshooting ).
<Not within 120 ± 20 ohms> Replace the BSW-ECU (master) (Refer to GROUP 54A - BSW-ECU ).