Code No. B1570: Passenger’s air bag cut off switch malfunction
Code No. B1573: Passenger’s air bag cut off switch circuit (power supply side) shorted
Code No. B1574: Passenger’s air bag cut off switch circuit open
Code No. B1575: Passenger’s air bag cut off switch circuit (earth side) shorted


caution If diagnosis code B1570, B1573, B1574 or B1575 are set in the SRS-ECU, always diagnose the CAN bus lines.

OPERATION



DIAGNOSIS CODE SET CONDITIONS




Code No.
 Symptom
B1570
 Malfunction of passenger’s air bag cut off switch
B1573
 Short to the power supply in the common terminal harness
B1574
 Malfunction of the common terminal or open circuit in its harness
B1575
 Short to body earth in the common terminal harness

PROBABLE CAUSES



  • Malfunction of the passenger’s air bag cut off switch

  • Damaged wiring harnesses or connectors

  • Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnostics



Q. Is the check result normal?





STEP 2. Check whether the diagnosis code is reset.



(1)Connect the negative battery terminal.
(2)After erasing the diagnosis code memory, check the diagnosis code again.
(3)Disconnect the negative battery terminal.

Q. Is the diagnosis code No.B1570, B1573, B1574 or B1575 set?





STEP 3. Check the passenger’s air bag cut off switch.



Q. Is the check result normal?





STEP 4. Check the passenger’s air bag cut off switch circuit. Resistance measurement at SRS-ECU 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)Switch the passenger’s air bag cut off switch to air bag ON side.
(4)Measure the resistance between POF-, POFO line.
OK: 820 ± 20 Ω
(5)Switch the passenger’s air bag cut off switch to air bag OFF side.
(6)Measure the resistance between POF-, POFO line.
OK: Continuity (less than 2 Ω)

Q. Is the check result normal?





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)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)Disconnect the passenger’s air bag cut off switch connector.
(4)Take the measurements below at the SRS-ECU harness side connector.

  • Continuity between POF-, POFO line and body earth
OK: No continuity

Q. Is the check result normal?





STEP 6. Voltage 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)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)Disconnect the passenger’s air bag cut off switch connector.
(4)Connect the negative battery terminal.
(5)Ignition switch: ON
(6)Take the measurements below at the SRS-ECU harness side connector.

  • Voltage between POF-, POFO line and body earth
OK: 1 V or less

Q. Is the check result normal?





STEP 7. Check whether the diagnosis code is reset.


Q. Is diagnosis code No.B1570, B1573, B1574 or B1575 set?