Code No.B1471: Seat belt pre-tensioner squib (LH)
open-circuited
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caution |
If diagnosis code B1471 is set in the SRS-ECU, always
diagnose the CAN main bus line.
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OPERATION
The SRS-ECU judges how severe a collision is by
detecting signals from the front impact sensors and the front air bag analogue
G-sensor. If the impact is over a predetermined level, the SRS-ECU sends an
ignition signal. At this time, if the front air bag safing G-sensor is on, the
pre-tensioner will deploy.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if there
is abnormal resistance between the input terminals of the seat belt
pre-tensioner (LH) (squib).
PROBABLE CAUSES
- Improper connector contact
- Open circuit in the seat belt pre-tensioner (LH) (squib) circuit
- Malfunction of the SRS-ECU
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STEP 1.M.U.T.-III CAN bus diagnostics
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Use the M.U.T.-III to diagnose the CAN bus
lines.
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Q.
Is the check result normal?
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Go to Step 2.
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Repair
the CAN bus line (Refer to GROUP 54D, Diagnosis ).
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STEP 2. Check whether the diagnosis code is reset.
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Check again if the diagnosis code is
set.
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(1)Erase the diagnosis code.
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(2)Ignition: "LOCK" (OFF) position to "ON"
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(3)On completion, check that the diagnosis code is not
reset.
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Q.
Is the diagnosis code set?
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Go to Step 3.
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There
is an intermittent malfunction such as poor engaged connector(s) or open
circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
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STEP 3. Check the seat belt pre-tensioner (LH).
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(1)Disconnect the negative battery terminal.
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(2)Disconnect seat belt pre-tensioner (LH) connector
E-16.
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![](../../../img/52/AC006042DL00ENG.png)
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(3)Connect special tool dummy resistor
(MB991865) to special tool resistor harness (MB991866). (4)Connect
special tool MB991866 to the E-16 harness side connector. (5)Connect the
negative battery terminal. (6)Erase the diagnosis code from memory, and
then check the diagnosis code.
Q.
Is diagnosis code B1471 set?
Go to Step 4.
Replace the seat belt with
pre-tensioner (LH) (Refer to ).
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STEP 4. Resistance measurement between SRS-ECU connector D-25 (terminal
No.7 and 8) and the seat belt pre-tensioner (LH) connector E-16 (terminal
No.1 and 2).
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(1)Disconnect the negative battery terminal.
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(2)Disconnect SRS-ECU connector D-25 and seat belt
pre-tensioner (LH) connector E-16.
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(3)
caution |
Do not insert a test probe into the terminal from
its front side directly, as the connector contact pressure may be
weakened.
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Check for continuity between the following
terminals.
- SRS-ECU connector D-25 (terminal No.7) and the special tool (terminal
No.1)
- SRS-ECU connector D-25 (terminal No.8) and the special tool (terminal
No.2)
OK: Continuity (Less than 2 Ω)
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Q.
Are the check results normal?
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Go to Step 5.
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Repair
the harness wires between SRS-ECU connector D-25 (terminal No.7 and 8) and
seat belt pre-tensioner (LH) connector E-16 (terminal No.1 and 2).
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STEP 5. Check whether the diagnosis code is reset.
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Q.
Is diagnosis code B1471 set?
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Replace the SRS-ECU (Refer to ).
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An
intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with
Intermittent Malfunction ).
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