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DTC B1610: Seat belt pre-tensioner (passenger’s side) (squib) system (open circuit of squib circuit)
 
 
cautionIf DTC B1604 is set in the SRS-ECU, always diagnose the CAN main bus line.
 
 
CIRCUIT OPERATION
The SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the analog G-sensor in the SRS-ECU. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, the pre-tensioner will deploy.
 
 
DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the passenger's seat belt pre-tensioner (squib).
 
 
TROUBLESHOOTING HITS
  • Improper connector contact
  • Open circuit in the passenger's seat belt pre-tensioner (squib) circuit
  • Malfunction of the SRS-ECU
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). 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. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Go to Step 3.
There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 3. 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 (passenger'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 (passenger'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 B1610 set?
Go to Step 4.
Replace the seat belt with pre-tensioner (passenger’s side) (Refer to ).
 
STEP 4. Resistance measurement at the SRS-ECU connector and the seat belt pre-tensioner (passenger's side) connector.
(1) Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2) While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the SRS-ECU connector.
(3)
dangerTo release the SRS-ECU connector short spring in the following operations, disconnect 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 (passenger's side) 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 [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] such as cable tie between the PTA+, PTA- line, and the short spring, and release the short spring.

(5) Connect special tool resistor harness (MB991884) to the removed seat belt pre-tensioner (passenger's side) harness side connector.
(6) Take the measurements below at the resistor harness and SRS-ECU harness side connector.
  • Continuity PTA+ line between SRS-ECU connector and resistor harness connector
  • Continuity PTA- line between SRS-ECU connector to resistor harness connector
OK: Continuity (less than 2 Ω)
Is the check result normal?
Go to Step 5.
Repair the wiring harness PTA+, PTA- line between the SRS-ECU connector and the seat belt pre-tensioner (passenger's side) connector.
 
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC B1610 set?
Replace SRS-ECU (Refer to SRS-ECU ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).