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DTC B1527: Seat Belt Switch (Driver’s side) Circuit Open
 
 
cautionIf DTC B1527 are stored in the SRS-ECU, always diagnose the CAN main bus lines.
 
 
CIRCUIT OPERATION
The SRS-ECU determines whether the seat belt is fastened or not according to the connection location of the seat belt switch in the seat buckle.
 
 
DTC SET CONDITIONS
The DTC is stored when the seat belt switch output current is not within the specified range.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the seat belt switch (driver’s side)
  • Damaged wiring harnesses or connectors
  • 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 stored.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is stored.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC stored?
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. Seat belt switch (driver’s side) check.
Refer to GROUP 52A, Front Seat Belt
Is the check result normal?
Go to Step 4.
Replace the seat belt switch (driver’s side) (Refer to GROUP 52A, Front Seat Belt ).
 
STEP 4. Check the harness short circuit between seat belt switch (driver’s side) connector and the SRS-ECU connector.
(1) Disconnect the negative battery terminal.
(2) Disconnect the seat belt switch (driver’s side) connector.
(3) 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.
(4) Connect the negative battery terminal.
(5) Ignition switch: ON.
(6) Measure the voltage between PBS-, PBSO line and body ground.
Voltage should measure 1 V or less.
Is the check result normal?
Go to Step 5.
Repair the harness wires PBS-, PBSO line between SRS-ECU connector and the seat belt switch (driver’s side) connector.
 
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is stored.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is stored.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC B1527 stored?
Replace the SRS-ECU (Refer to ).
The procedure is complete.