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DTC B1858: SW Connection
 
 
cautionWhen replacing the ECU, always check that the communication circuit is normal.
 
 
TROUBLE JUDGMENT
Check Conditions
  • When all of the following conditions are satisfied:
    • Ignition switch: ON
    • Indicator lights: Working
Judgment Criterion
  • When the system detects an open circuit in the SOS switch/information switch indicator light system for 5 second or more.
 
 
TROUBLESHOOTING HINTS
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • The ECALL&BCALL switch may be defective
  • The TCU may be defective
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Resistance measurement at the ECALL&BCALL switch connector (terminal No. 2).
(1) Disconnect the ECALL&BCALL switch connector, and measure at the wiring harness side.
(2) Check the resistance between the ECALL&BCALL switch connector (terminal No. 2) and body ground.
OK: OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 2.
Repair the connector(s) or wiring harness.
 
STEP 2. Check the SOS switch/information switch indicator light.
Check that the SOS switch/information switch indicator light illuminates. Refer to .
Is the check result normal?
Go to Step 3.
Replace the ECALL&BCALL switch (Refer to ).
 
STEP 3. Resistance measurement at between the TCU connector (IND1, IND4, IND5, IND6 terminals).
(1) Disconnect the TCU and the ECALL&BCALL switch connector, and measure at the wiring harness side.
(2) Check the resistance between the TCU connector (IND1 terminal) and the ECALL&BCALL switch connector (terminal No.4).
OK: The resistance should be 2 ohms or less
(3) Check the resistance between the TCU connector (IND4 terminal) and the ECALL&BCALL switch connector (terminal No.5).
OK: The resistance should be 2 ohms or less
(4) Check the resistance between the TCU connector (IND5 terminal) and the ECALL&BCALL switch connector (terminal No.15).
OK: The resistance should be 2 ohms or less
(5) Check the resistance between the TCU connector (IND6 terminal) and the ECALL&BCALL switch connector (terminal No.16).
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Check again if the DTC is set in the TCU.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Erase the DTC.
(3) Turn the ignition switch from OFF position to ON position.
(4) Check the DTC.
Is the DTC set?
Replace the TCU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).