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DTC B1852: Collision Signal Connection
 
 
caution
  • When you check the SRS-ECU, disconnect the negative (-) battery terminal and wait for 60 seconds or more before starting work. Insulate the disconnected (-) terminal by wrapping the tape (Refer to GROUP 52B - Service Precautions ).
  • When replacing the ECU, always check that the communication circuit is normal.
 
 
TROUBLE JUDGMENT
Check Conditions
  • Ignition switch: ON
Judgment Criterion
  • If the collision signal from the SRS-ECU cannot be received for 5 seconds or more.
 
 
TROUBLESHOOTING HINTS
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • The SRS-ECU may be defective
  • The TCU may be defective
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the SRS-ECU DTC is set.
(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) Turn the ignition switch to the "ON" position.
(3) Check whether the SRS-ECU DTC B1498 is set.
Is DTC B1498 set?
Diagnose the SRS-ECU (Refer to GROUP 52B - Diagnostic Trouble Code Chart <SRS-ECU> ).
Go to Step 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).
Is the check result normal?
Replace the SRS-ECU.
Go to Step 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
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) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) 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 ).