Code No.26: Driver’s seat belt pre-tensioner (squib) system
(short-circuited between terminals of the squib circuit)
![](../../../img/52/W4X52X009A00ENG.png)
OPERATION
The SRS-ECU judges how severe a collision is by
detecting signals from the front impact sensors and the front air bag
analog G-sensor. If the impact is over a predetermined level, the
SRS-ECU outputs 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
one driver’s pre-tensioner squib wire shorted to the other.
However, if no diagnosis code resets, the SRS warning lamp will be
switched off (diagnosis code will be retained).
PROBABLE CAUSES
- Improper engaged connector or defective short
spring*
- Short circuit between the driver’s seat belt pre-tensioner
(squib) circuit terminals
- Damaged connector(s)
- Malfunction of the SRS-ECU
note |
*: The squib circuit connectors
integrate a "short" spring (which prevents the air bag 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). Therefore, if
connector C-147, C-148 or D-32 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 diagnosis code
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Q.
Is diagnosis code 34 set?
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Go to Step
2.
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Go to Step
3.
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STEP 2. Connector lock check: SRS-ECU connector C-147
(M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC311438AF00ENG.png)
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(2)Disconnect the connectors C-147
and then reconnect them. (3)Connector the negative
battery terminal. (4)Erase the diagnosis code memory, and
check the diagnosis code.
Q.
Is diagnosis code 26 set?
Go to Step
3.
The
procedure is complete. It is assumed that diagnosis code 26
set as connector C-147 was engaged improperly.
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STEP 3. Connector lock check: SRS-ECU connector C-147
and driver’s seat belt pre-tensioner connector
D-32 (M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC311438AF00ENG.png)
![](../../../img/52/AC313414AV00ENG.png)
![](../../../img/52/AC313429AN00ENG.png)
![](../../../img/52/AC300147AK00ENG.png)
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(2)Disconnect connectors C-147,
C-148 or D-32, and then reconnect them. For connector D-32,
use a flat-tipped screwdriver to pull out the locking button
at the harness side connector, and then disconnect the
connector. (3)Connector the negative battery
terminal. (4)Erase the diagnosis code memory, and check
the diagnosis code.
Q.
Is diagnosis code 26 set?
Go to Step
4.
The
procedure is complete. It is assumed that diagnosis code 26
set as connector C-147, C-148, or D-32 was engaged
improperly.
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STEP 4. Check the diagnosis code by connecting a dummy
resistor (M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC313414AV00ENG.png)
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(2)Disconnect intermediate
connector C-148 (pre-tensioner harness and instrument panel
harness connection).
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![](../../../img/52/AC006042CG00ENG.png)
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(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991866). (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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Connect special tool (MB991866) to the C-148 harness
side connector by backprobing. (5)Connect the negative
battery terminal. (6)Erase diagnosis code memory, and
then check the diagnosis code.
Q.
Is diagnosis code 26 set?
Go to Step
5.
Go to Step
6.
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STEP 5. Resistance measurement at the SRS-ECU connector
C-147.
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC311438AF00ENG.png)
![](../../../img/52/AC313414AV00ENG.png)
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(2)Disconnect SRS-ECU connector
C-147.
danger |
To prevents the air bag from
deploying unintentionally, disconnect the
driver’s seat belt pre-tensioner connector
C-148 to short the squib circuit.
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(3)Disconnect intermediate connector C-148
(pre-tensioner harness and instrument panel harness
connection).
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![](../../../img/52/AC208510AD00ENG.png)
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(4)
caution |
Insert an insulator such as a
cable tie to a depth of 4mm or more, otherwise
the short bar will not be released.
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Insert a cable tie [3 mm wide, 0.5 mm
thick] between terminals 5, 6 and the short bar to
release the short spring.
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![](../../../img/52/AC208507AD00ENG.png)
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(5)
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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Resistance measurement between C-147 harness side
connector terminals 5 and 6. OK: Open
circuit
Q.
Is the check result normal?
Go to Step
7.
Repair
the harness wires between SRS-ECU connector C-147 (terminal
No.5 and 6) and harness side connector D-32 (terminal No.1
and 2).
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STEP 6. Resistance measurement at intermediate connector
C-148.
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(1)Disconnect the negative battery
terminal.
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![](../../../img/52/AC313429AN00ENG.png)
![](../../../img/52/AC300147AK00ENG.png)
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(2)
danger |
To prevents the air bag from
deploying unintentionally, disconnect the
driver’s seat belt pre-tensioner connector
D-32 to short the squib circuit.
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(3)Disconnect driver’s seat belt pre-tensioner
connector D-32. Use a flat-tipped screwdriver to pull out
the locking button at the harness side connector, and then
disconnect the connector.
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![](../../../img/52/AC313414AV00ENG.png)
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(4)Disconnect intermediate
connector C-148 (pre-tensioner harness and instrument panel
harness connection).
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![](../../../img/52/AC303537AI00ENG.png)
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(5)
caution |
Insert an insulator such as a
cable tie to a depth of 4mm or more, otherwise
the short bar will not be released.
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Insert a cable tie [3 mm wide, 0.5 mm
thick] between terminals 1, 2 and the short spring to
release the short spring.
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![](../../../img/52/AC304086AC00ENG.png)
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(6)
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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Resistance measurement between C-148 harness side
connector terminals 1 and 2. OK: Open
circuit
Q.
Is the check result normal?
Replace the
driver’s seat belt pre-tensioner (Refer to ).
Repair the harness
wires between driver’s seat belt pre-tensioner
connector D-32 (terminal No.1 and 2) and pre-tensioner side
connector C-148 (terminal No.1 and 2).
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STEP 7. Check whether the diagnosis code is
reset.
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Q.
Is diagnosis code 26 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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