[Previous][Next]
DTC B1603 Seat belt pre-tensioner (driver’s side) (squib) system (short circuit between squib circuit terminals)
 
 
cautionIf DTC B1603 is set in SRS-ECU, be sure to diagnose the CAN bus line.
 
 
OPERATION
Only when the frontal impact exceeding the threshold is simultaneously detected (turned ON) by the front impact sensor as well as by the analog G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the seat belt pre-tensioner (squib).
 
 
TROUBLE JUDGMENT
The code is set when the short circuit occurs between the terminals of SRS-ECU seat belt pre-tensioner (driver’s side) (squib) circuit.
 
 
PROBABLE CAUSES
  • Damaged short spring *
  • Short circuit between terminals of seat belt pre-tensioner (driver’s side) (squib) circuit
  • Damaged connector(s)
  • Malfunction of SRS-ECU
  • Insufficient press of locking button or locking button not pressed
note*: The squib connectors integrate a short spring (which prevents the seat belt pre-tensioner 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 B1603 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: seat belt pre-tensioner (driver’s side)
(1) Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2) After disconnecting the seat belt pre-tensioner (driver's side) harness side connector, connect the connector again. For the seat belt pre-tensioner (driver's side) harness side connector disconnection, use the flat-tipped screwdriver to pull out the harness side connector locking button. After releasing the lock, disconnect the harness side connector.
(3) Connect the negative battery terminal.
(4) After erasing the DTC memory, check the DTC again.
(5) Disconnect the negative battery terminal.
Is DTC B1603 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 seat belt pre-tensioner (driver's side) harness side connector.
(3) Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884).
(4) Connect special tool resistor harness to the seat belt pre-tensioner (driver's side) 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 B1603 set?
Go to Step 5.
Replace the seat belt with pre-tensioner (driver’s side) (Refer to ).
 
STEP 5. Resistance check 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)
dangerDisconnect this seat belt pre-tensioner connector, 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 seat belt pre-tensioner (driver's side) harness side connector.
(4) Take the measurements below at the SRS-ECU harness side connector.
  • Continuity between PTD-, PTD+ line
OK: No continuity
Is the check result normal?
Go to Step 6.
Repair the wiring harness PTD-, PTD+ line between the SRS-ECU connector and the seat belt pre-tensioner (driver's side) connector.
 
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Is DTC B1603 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 ).