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 Code No.B1576: Passenger’s air bag
cut off switch circuit (power supply side) shorted
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
B1574
Malfunction of the common terminal or open circuit in its harness
B1575
Short to body earth in the common terminal harness
B1576
Short to the power supply 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. Connector check: B-108 passenger’s air
bag cut off switch connector
Q.
Is the check result normal?
Go to Step 2
Replace the defective connector.
STEP 2. 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 3
Replace passenger’s air bag cut off switch (Refer to ).
STEP 3. Check the passenger’s air bag cut off switch circuit.
Resistance measurement at the B-112 SRS-ECU connector.
(1)Disconnect the negative auxiliary battery terminal.
(2)Disconnect the B-112 SRS-ECU connector.
(3)Switch the passenger’s air bag cut off switch to air bag ON side.
(4)Measure the resistance between terminal 24 and terminal 25. OK: 820 ± 82 Ω
(5)Switch the passenger’s air bag cut off switch to air bag OFF side.
(6)Measure the resistance between terminal 24 and terminal 25. OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Go to Step 4
Repair the harness wires between SRS-ECU connector B-112 (terminal No.24 and 25)
and passenger’s air bag cut off switch connector B-108 (terminal No.1 and 4).
STEP 4. Resistance measurement at the B-112 SRS-ECU connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative
auxiliary battery terminal is connected, disconnect it.
(2)Disconnect the B-112 SRS-ECU connector.
(3)Disconnect the B-108 passenger’s air bag cut off switch connector.
(4)Take the measurements below at the B-112 harness side connector.
Continuity between terminal No. 24/25 and body
earth
OK: No continuity
Q.
Is the check result normal?
Go to Step 5
Repair the harness wires between SRS-ECU connector B-112 (terminal No.24 and 25)
and passenger’s air bag cut off switch connector B-108 (terminal No.1 and 4).
STEP 5. Voltage measurement at the B-112 SRS-ECU connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative
auxiliary battery terminal is connected, disconnect it.
(2)Disconnect the B-112 SRS-ECU connector.
(3)Disconnect the B-108 passenger’s air bag cut off switch connector.
(4)Connect the negative auxiliary battery terminal.
(5)Electric motor switch to the "ON" position
(6)Take the measurements below at the B-112 harness side connector.
Voltage between terminal No. 24/25 and body
earth
OK: 1 V or less
Q.
Is the check result normal?
Go to Step 6
Repair the harness wires between SRS-ECU connector B-112 (terminal No.24 and 25)
and passenger’s air bag cut off switch connector B-108 (terminal No.1 and 4).
STEP 6. Check whether the diagnosis code is reset.
Q.
Is diagnosis code No.B1574, B1575 or B1576 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00 - How to
Cope with Intermittent Malfunction ).
)
)
)
Go to Step 2
Replace the defective connector.
).