Code No.B1609 Seat belt pre-tensioner (passenger’s side)
(squib) system (short circuit between squib circuit
terminals)
| caution |
If diagnosis code B1609 is set in the
SRS-ECU, be sure to diagnose the CAN bus line.
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OPERATION
Only when the frontal impact exceeding the
threshold is simultaneously detected (turned ON) by the front impact
sensor as well as by the analogue G-sensor in SRS-ECU, the ignition
signal is sent from SRS-ECU to the seat belt pre-tensioner
(squib).
TROUBLE JUDGEMENT
The code is set when the short circuit
occurs to between the terminals of SRS-ECU seat belt pre-tensioner
(passenger’s side) (squib) circuit.
PROBABLE CAUSES
- Damaged short spring *
- Short circuit between terminals of seat belt pre-tensioner
(passenger’s side) (squib) circuit
- Damaged connector(s)
- Malfunction of SRS-ECU
- Insufficient press of locking button or locking button not
pressed
| note |
*: The squib circuit connectors
integrate a short spring (which prevents the seat belt
pre-tensioner from being unintentionally deployed because of
static electricity by shorting the positive wire to the
earth wire in the squib circuit when the connectors are
disconnected). Therefore, when the above codes are set, the
short spring may not be released due to the damaged
connector even when the connectors are connected.
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STEP 1. M.U.T.-III CAN bus diagnostics.
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Use 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 54C - Troubleshooting  ).
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STEP 2. Check whether the diagnosis code is set
again.
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(1)Connect the negative battery terminal.
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(2)After erasing the diagnosis code memory, check
the diagnosis code again.
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(3)Disconnect the negative battery
terminal.
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Q.
Is diagnosis code No. B1609 set?
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Go to Step
3.
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Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection Service Points - How
to Cope with Intermittent Malfunction ).
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STEP 3. Connector check: SRS-ECU, seat belt
pre-tensioner (passenger’s side).
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(1)Check that the negative battery terminal is
disconnected. If the negative battery terminal is connected,
disconnect it.
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(2)Disconnecting the SRS-ECU connector, connect it
again.
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(3) After disconnecting the seat
belt pre-tensioner (passenger’s side) harness side
connector, connect the connector again. For the seat belt
pre-tensioner (passenger’s side) harness side
connector disconnection, use the flat-tipped screwdriver to
pull out the harness side connector locking button. After
releasing the lock, disconnect the harness side
connector.
(4)Connect the negative battery
terminal.
(5)After erasing the diagnosis code memory,
check the diagnosis code again.
(6)Disconnect the
negative battery terminal.
Q.
Is diagnosis code No. B1609 set?
Go to Step
4.
Replace
the connector concerned.
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STEP 4. Diagnosis check by dummy resistor
connection.
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(1)Check that the negative battery terminal is
disconnected. If the negative battery terminal is connected,
disconnect it.
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(2)Use the flat-tipped screwdriver
to pull out the locking button of harness side connector.
After releasing the lock, disconnect the seat belt
pre-tensioner (passenger’s side) harness side
connector.
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(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991884).
(4)Connect special tool resistor harness to
the seat belt pre-tensioner (passenger’s side) harness
side connector.
(5)Connect the negative battery
terminal.
(6)After erasing the diagnosis code memory,
check the diagnosis code again.
(7)Disconnect the
negative battery terminal.
Q.
Is diagnosis code No. B1609 set?
Go to Step
5.
Replace
the seat belt with pre-tensioner (passenger’s side)
(Refer to ).
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STEP 5. Resistance check at the SRS-ECU
connector.
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(1)Check that the negative battery terminal is
disconnected. If the negative battery terminal is connected,
disconnect it.
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(2)Disconnect the SRS-ECU connector.
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(3)
| danger |
To release the SRS-ECU
connector short spring in the following
operations, disconnect this seat belt
pre-tensioner connector, and keep the squib
circuit shorted.
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Use the flat-tipped screwdriver to pull out the
locking button of harness side connector. After releasing
the lock, disconnect the seat belt pre-tensioner
(passenger’s side) harness side connector.
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(4)
| caution |
The short spring may not be
released due to the insufficient insertion.
Therefore, insert the insulator for 4 mm or
more.
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Insert an insulator (width: 3 mm, thickness: 0.5 mm)
such as cable tie between the PTA+, PTA- line, and the
short spring, and release the short spring.
(5)Take the
measurements below at the SRS-ECU harness side connector.
- Continuity between PTA+, PTA- line
OK: No continuity
Q.
Is the check result normal?
Go to Step
6.
Repair
the wiring harness PTA+, PTA- line between the SRS-ECU
connector and the seat belt pre-tensioner (passenger’s
side) connector.
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STEP 6. Check whether the diagnosis code is set
again.
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Q.
Is diagnosis code No. B1609 set?
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Replace SRS-ECU
(Refer to ).
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Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection Service Points - How
to Cope with Intermittent Malfunction ).
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