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Diagnostic Item 18: Diagnose the lines between the joint connectors (CAN3 and CAN4).
 
 
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 "diagnose the lines between the joint connectors (CAN3 and CAN4)" when the scan tool (M.U.T.-IIISE) checks the periodically sent data from each ECU and cannot receive the ECM data.
  • ECM
  • ACC/FCM-ECU <Vehicles with ACC>
 
 
TROUBLE JUDGMENT CONDITIONS
The scan tool (M.U.T.-IIISE) judges the trouble when the periodically sent data from ECM cannot be received.
  • ECM
  • ACC/FCM-ECU <Vehicles with ACC>
 
 
TROUBLESHOOTING HINTS
Damaged harness wires and connectors
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: joint connector (CAN3) and joint connector (CAN4)
cautionThe strand end of the twist wire should be within 10 cm (3.9 inches) 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 joint connector (CAN4).
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect the joint connector (CAN3) and the joint connector (CAN4), 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.10 and joint connector (CAN4) terminal No.11
OK: The resistance should be 2 ohms or less
(5) Continuity between joint connector (CAN3) terminal No.21 and joint connector (CAN4) terminal No.22
OK: The resistance should be 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> Follow diagnosis item 19 and 20. Refer to .
<Either or all of the resistances measure more than 2 ohms> Repair the wiring harness between joint connector (CAN3) and joint connector (CAN4).