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


According to the passenger’s air bag cut off switch connecting position, the SRS-ECU judges the deployment and non-deployment of passenger’s (front) air bag.

DIAGNOSIS CODE SET CONDITIONS


Diagnosis code is set when the resistance between input terminals of the passenger’s air bag cut off switch is without the standard value.
Cause of trouble in each diagnosis code is as follows.
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





DIAGNOSIS PROCEDURE


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


Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

Go to Step 2.

Repair the CAN bus lines (Refer to GROUP 54C, Diagnosis-Can Bus Diagnostic Chart ).

STEP 2. Check whether the diagnosis code is reset.


Check again if the diagnosis code is set.
(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?

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


Check of a passenger’s air bag cut off switch (Refer to ).

Q. Is the check result normal?

Go to Step 4.

Replace passenger’s air bag cut off switch (Refer to .)

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?

Go to Step 5.

Repair the harness wires POF-, POFO line between SRS-ECU connector and passenger’s air bag cut off switch connector.

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?

Go to Step 6.

Repair the harness wires POF-, POFO line between SRS-ECU connector and passenger’s air bag cut off switch connector.

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?

Go to Step 7.

Repair the harness wires POF-, POFO line between SRS-ECU connector and passenger’s air bag cut off switch connector.

STEP 7. Check whether the diagnosis code is reset.


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

Replace the SRS-ECU (Refer to ).

An intermittent malfunction is suspected (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).