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DTC B1440 Curtain air bag module (RH) (squib) system (short circuit between squib circuit terminals)
 
 
cautionIf DTC B1440 is set in SRS-ECU, be sure to diagnose the CAN bus line.
 
 
OPERATION
In case of side collision, when the impact exceeding the threshold is applied to the vehicle, and when the impact is simultaneously detected (turned ON) by the side impact sensor as well as by the analog G-sensor in SRS-ECU, the ignition signal is sent from SRS-ECU to the curtain air bag module (squib) of impacted side.
 
 
TROUBLE JUDGMENT
The code is set when the short circuit occurs between the terminals of SRS-ECU curtain air bag module (squib) circuit.
 
 
PROBABLE CAUSES
  • Damaged short spring *
  • Short circuit between terminals of curtain air bag module (squib) circuit
  • Damaged connector(s)
  • Malfunction of SRS-ECU
  • Insufficient press of locking button or locking button not pressed
note*: The squib circuit connectors integrate a short spring (which prevents the air bags from being unintentionally deployed because of static electricity by shorting the positive wire to the ground wire in the squib circuit when the connectors are disconnected). Therefore, when the above codes are set, the short spring may not be released due to the damaged connector even when the connectors are connected.
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
(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 ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
(1) Connect the negative battery terminal.
(2) After erasing the DTC memory, check the DTC again.
(3) Disconnect the negative battery terminal.
Is DTC B1440 set?
Go to Step 3.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
 
STEP 3. Connector check: SRS-ECU, curtain air bag module (RH).
(1) Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2) After disconnecting the SRS-ECU connector, connect it again.
(3) After disconnecting the curtain air bag module (RH) harness side connector, connect the connector again. For the curtain air bag module (RH) connector disconnection, use the flat-tipped screwdriver to pull out the harness side connector locking button. After releasing the lock, disconnect the connector.
(4) Connect the negative battery terminal.
(5) After erasing the DTC memory, check the DTC again.
(6) Disconnect the negative battery terminal.
Is DTC B1440 set?
Go to Step 4.
Replace the connector concerned.
 
STEP 4. Diagnosis check by dummy resistor connection.
(1) Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2) Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the curtain air bag module (RH) harness side connector.
(3) Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884).
(4) Connect the special tool resistor harness to the curtain air bag module (RH) harness side connector.
(5) Connect the negative battery terminal.
(6) After erasing the DTC memory, check the DTC again.
(7) Disconnect the negative battery terminal.
Is DTC B1440 set?
Go to Step 5.
Replace the curtain air bag module (RH) (Refer to .)
 
STEP 5. Resistance measurement at the SRS-ECU connector.
(1) Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2) Disconnect the SRS-ECU connector.
(3)
dangerTo release SRS-ECU wiring harness side connector short spring in the following operations, disconnect curtain air bag module connector in advance, and keep the squib circuit shorted.
Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the curtain air bag module (RH) harness side connector
(4)
cautionThe short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm (0.16 inch) or more.
Insert an insulator [width: 3 mm (0.12 inch), thickness: 0.5 mm (0.02 inch)] such as cable tie between the CRS-, CRS+ line and the short spring, and release the short spring.
(5) Take the measurements below at the SRS-ECU harness side connector.
  • Continuity between CRS-, CRS+ line
OK: No continuity
Is the check result normal?
Go to Step 6.
Repair the wiring harness CRS-, CRS+ line between the SRS-ECU connector and the curtain air bag module (RH) connector.
 
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Is DTC B1440 set?
Replace SRS-ECU (Refer to ).
Intermittent Malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).