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Diagnostic Item 8: Diagnose shorts between CAN_H and L lines (GW-CAN-C). <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.
 
 
TROUBLE JUDGMENT
When all of the following conditions are met, the scan tool (M.U.T.-IIISE) determines that a short circuit is present between CAN_L and CAN_H lines.
  • The scan tool (M.U.T.-IIISE) cannot receive the periodic transmission data from any ECUs.
  • The voltage between CAN-C (CAN_L and CAN_H lines) is 1.0 V or more, 4.0 V or less.
  • The resistance at CAN-C (CAN_L and CAN_H lines) is 2 ohms or less.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Malfunction of the gateway-ECU
  • Malfunction of the BSW-ECU (master)
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the GW-CAN-C. Resistance measurement at gateway-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 the gateway-ECU connector and the BSW-ECU (master) connector, and measure at the wiring harness side.
(2)
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.
(3) Resistance between the gateway-ECU connector terminal No.6 (CAN_H) and No.5 (CAN_L).
OK: 1 kΩ or more
Is the check result normal?
<1 kΩ or more> Go to Step 2.
<Less than 1 kΩ > Repair intermediate connectors, or the wiring harness between the gateway-ECU connector and the BSW-ECU (master) connector.
 
STEP 2. 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 between the BSW-ECU (master) connector terminal Nos.4 and 9.
OK: 120 ± 20 ohms
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
Is the check result normal?
<Within 120 ± 20 ohms> Go to Step 3.
<Not within 120 ± 20 ohms> Check the BSW-ECU (master) connector, and repair if necessary. If the BSW-ECU (master) connector is in good condition, replace the BSW-ECU (master).
 
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 between the gateway-ECU connector terminal Nos.5 and 6
OK: 120 ± 20 ohms
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
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> Check the gateway-ECU connector, and repair if necessary. If the gateway-ECU connector is in good condition, replace the gateway-ECU.