DTC B1852: Collision Signal Connection: Diagnosis

Required Special Tools 

• MB991223: Wiring harness set
• MB992006: Extra fine probe

1. STEP 1. Using scan tool (M.U.T.-IIISE), check whether the SRS-ECU DTC is set. 
   CAUTION: To 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).
   1. Connect scan tool (M.U.T.-IIISE). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) ."
   2. Turn the ignition switch to the "ON" position.
   3. Check whether the SRS-ECU DTC B1498 is set.

      Q: Is DTC B1498 set? 

      YES:  Diagnose the SRS-ECU (Refer to DIAGNOSTIC TROUBLE CODE CHART <SRS-ECU> ).

      NO:  Go to Step  2.

2. STEP 2. Voltage measurement at the SRS-ECU connector (TBAC terminal). 
   1. Disconnect the SRS-ECU connector, and measure at the wiring harness side.
   2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
   3. Check the voltage between the SRS-ECU connector (TBAC terminal) and body ground.

      OK: The voltage should measure approximately 12 volts (battery positive voltage). 

      Q: Is the check result normal? 

      YES:  Replace the SRS-ECU.

      NO:  Go to Step  3.

3. STEP 3. Resistance measurement at the TCU connector (CSIG terminal). 
   1. Disconnect the TCU connector and the SRS-ECU connector, and measure at the wiring harness side.
   2. Check the resistance between the TCU connector (CSIG terminal) and the SRS-ECU connector (TBAC terminal).

      OK: The resistance should be 2 ohms or less 

   3. Check the resistance between the TCU connector (CSIG terminal) and body ground.

      OK: No continuity 

      Q: Is the check result normal? 

      YES:  Go to Step  4.

      NO:  Repair the connector(s) or wiring harness.

4. 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. Erase the DTC.
   2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
   3. Check the DTC.

      Q: Is the DTC set? 

      YES:  Replace the TCU (Refer to TCU  ).

      NO:  The trouble can be an intermittent malfunction (Refer to How to use Troubleshooting/inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).