Code No.B1470: Seat Belt Pre-Tensioner (LH) (Squib) System Fault 1
(Short Circuit between Terminals of the Squib Circuit)
![](../../../img/52/W4X52E017A00ENG.png)
caution |
If diagnosis code B1470 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 engaged connector or defective short
spring*
- Short circuit between the seat belt pre-tensioner (LH) (squib)
circuit terminals
- Damaged connector(s)
- Malfunction of the SRS-ECU
note |
*: The squib circuit connectors
integrate a "short" spring (which prevents the seat belt
pre-tensioner from deploying unintentionally due to static
electricity by shorting the positive wire to the earth wire
in the squib circuit when the connectors are disconnected)
(Refer to ).
Therefore, if connector C-120 or D-19 is damaged or
improperly engaged, the short spring may not be released
when the connector is connected.
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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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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. M.U.T.-III diagnosis code
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caution |
To prevent damage to
M.U.T.-III MB991958, always turn the ignition
switch to the "LOCK" (OFF) position before
connecting or disconnecting M.U.T.-III
MB991958.
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(1)Turn the ignition switch to the "ON"
position.
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(2)Check if the diagnosis code is set.
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(3)Turn the ignition switch to the "LOOK (OFF)"
position.
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Q.
Is diagnosis code B1519 set?
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Go to Step 4
.
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Go to Step 5
.
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STEP 4. Connector lock check: SRS-ECU connector C-120
(M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC311438AE00ENG.png)
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(2)Disconnect the connectors C-120
and then reconnect them. (3)Connect the negative battery
terminal. (4)Erase the diagnosis code memory, and check
the diagnosis code.
Q.
Is diagnosis code B1470 set?
Go to Step 5
.
The
procedure is complete. It is assumed that diagnosis code
B1470 set as connector C-120, D-19 was engaged
improperly.
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STEP 5. Connector lock check: SRS-ECU connector C-120
and seat belt pre-tensioner (LH) connector D-19
(M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC311438AE00ENG.png)
![](../../../img/52/AC302393AC00ENG.png)
![](../../../img/52/AC103556AY00ENG.png)
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(2)Disconnect connectors C-120 and
D-19, and then reconnect them. For connector D-19, use a
flat-tipped screwdriver to unlock the locking button at the
harness side connector by withdrawing it toward you in two
stages, and then disconnect the connector. (3)Connect the
negative battery terminal. (4)Erase the diagnosis code
memory, and check the diagnosis code.
Q.
Is diagnosis code B1470 set?
Go to Step 6
.
The
procedure is complete. It is assumed that diagnosis code
B1470 set because connector C-120 or D-19 was engaged
improperly.
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STEP 6. Check the driver’s seat belt pre-tensioner
(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 withdrawing 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 then check
the diagnosis code.
Q.
Is diagnosis code B1470 set?
Go to Step 7
.
Replace
the seat belt pre-tensioner (LH) (Refer to ).
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STEP 7. Check the seat belt pre-tensioner (LH) circuit.
Resistance 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)
danger |
To prevent the seat belt
pre-tensioner from deploying unintentionally,
disconnect the seat belt pre-tensioner (LH)
connector D-19 to short the squib
circuit.
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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 withdrawing it
toward you in two stages, and then disconnect the
connector.
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![](../../../img/52/AC308175AD00ENG.png)
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(3)
caution |
Insert an insulator such as a
cable tie to a depth of 4mm or more, otherwise
the short spring will not be released.
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Insert a cable tie [3 mm wide, 0.5 mm
thick] between terminals 7, 8 and the short spring to
release the short spring.
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![](../../../img/52/AC312822BE00ENG.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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Check for continuity between C-120 harness side
connector terminals 7 and 8. OK: Open
circuit.
Q.
Is the check result normal?
Go to Step 8
.
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 8. Check whether the diagnosis code is
reset.
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Q.
Is diagnosis code B1470 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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