Code No.67: Driver’s seat belt pre-tensioner (squib) system
(short-circuited to the earth)
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
the driver’s seat belt pre-tensioner wire(s) are short-circuited
to the earth.
PROBABLE CAUSES
- Damaged wiring harnesses or connectors
- Short to the earth in the driver’s seat belt pre-tensioner
(squib) harness
- Malfunction of the SRS-ECU
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STEP 1. 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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(2)Disconnect intermediate
connector C-148 (pre-tensioner harness and instrument panel
harness connection).
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(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991866).
(4)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 check the diagnosis code.
Q.
Is diagnosis code 67 set?
 Go to Step
2.
 Go to Step
3.
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STEP 2. Resistance measurement at the SRS-ECU connector
C-147.
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(1)Disconnect the negative battery
terminal.
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(2)Disconnect SRS-ECU connector
C-147.
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(3)Disconnect intermediate
connector C-148 (pre-tensioner harness and instrument panel
harness connection).
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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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Resistance measurement between C-147 harness side
connector terminals 5, 6 and body earth.
OK:
Open circuit
Q.
Is the check result normal?
Go to Step 4
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Repair the
harness wire between SRS-ECU connector C-147 (terminal No. 5
and 6) and harness side connector C-148 (terminal No. 1 and
2).
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STEP 3. Resistance measurement at intermediate connector
C-148.
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(1)Disconnect the negative battery
terminal.
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(2)Disconnect intermediate
connector C-148 (pre-tensioner harness and instrument panel
harness connection).
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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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(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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Resistance measurement between C-148 harness side
connector terminals 1, 2 and body earth.
OK:
Open circuit
Q.
Is the check result normal?
Replace the
driver’s seat belt pre-tensioner (Refer to ).
Repair the harness
wire between pre-tensioner side connector (terminal No. 1
and 2) and driver’s seat belt pre-tensioner connector
D-32 (terminal No. 1 and 2).
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STEP 4. Check whether the diagnosis code is
reset.
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Q.
Is diagnosis code 67 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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