Code No.B1473: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Power
Supply Circuit (Short-Circuit to Power Supply)
![](../../../img/52/W4X52E017A00ENG.png)
caution |
If diagnosis code B1473 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.
DTC SET CONDITIONS
Thisdiagnosis code is set if there is abnormal
resistance between the input terminals of the seat belt pre-tensioner (LH)
(squib).
TROUBLESHOOTING HITS
- Damaged wiring harnesses or connectors
- Short to the power supply in the seat belt pre-tensioner (LH) (squib)
harness
- 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 54F, 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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Go to Step 5.
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STEP 3. Check the seat belt pre-tensioner (LH) (M.U.T.-III diagnosis
code).
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(1)Disconnect the negative battery terminal.
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![](../../../img/52/AC302393AC00ENG.png)
![](../../../img/52/AC103556AY00ENG.png)
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(2)Disconnect seat belt pre-tensioner (LH)
connector D-19. Use a flat-tipped screwdriver to unlock the locking button
at the harness side connector by with drawing it toward you in two stages,
and then disconnect the connector.
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![](../../../img/52/AC103283AV00ENG.png)
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(3)Connect special tool dummy resistor
(MB991865) to special tool resistor harness (MB991884). (4)Connect
special tool MB991884 to the D-19 harness side connector. (5)Connect the
negative battery terminal. (6)Erase diagnosis code memory, and check the
diagnosis code.
Q.
Is diagnosis code B1473 set?
Go to Step 4.
Replace the seat belt pre-tensioner
(LH) (Refer to ).
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STEP 4. Check the driver’s seat belt pre-tensioner circuit.
Voltage measurement at the SRS-ECU connector C-120.
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![](../../../img/52/AC311438AE00ENG.png)
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(1)Disconnect SRS-ECU connector C-120.
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![](../../../img/52/AC302393AC00ENG.png)
![](../../../img/52/AC103556AY00ENG.png)
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(2)Disconnect seat belt pre-tensioner (LH)
connector D-19. Use a flat-tipped screwdriver to unlock the locking button
at the harness side connector by with drawing it toward you in two stages,
and then disconnect the connector. (3)Turn the ignition switch to the
"ON" position.
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![](../../../img/52/AC308187AD00ENG.png)
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(4)
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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Measure the voltage between C-120 harness side connector terminals
7, 8 and body earth. OK: 0 V
Q.
Is the check result normal?
Go to Step 5.
Repair the harness wires between
SRS-ECU connector C-120 (terminal No.7 and 8) and seat belt pre-tensioner
(LH) connector D-19 (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 B1473 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 Use
Troubleshooting/Inspection Service Points ).
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