Code No. B1628:
Front passenger’s lap pre-tensioner (squib) system (shorted to squib
circuit power supply)
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If diagnosis code No. B1628
is set in the SRS-ECU, be sure to diagnose the CAN bus line.
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Only when the frontal collision impact that
exceeds the threshold is simultaneously detected
(turned ON) by the front impact sensor as well as by the analogue G-sensor
in SRS-ECU, the electric
current is supplied from SRS-ECU to the lap pre-tensioner (squib).
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The code is set when the SRS-ECU
passenger’s lap pre-tensioner (squib) circuit
is shorted to power supply.
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- Poor contact of connector
- Passenger’s lap pre-tensioner (squib) harness shorted to power
supply
- Malfunction of SRS-ECU
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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. B1628 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. 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 lap pre-tensioner 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 (MB991884) to the lap pre-tensioner 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. B1628 set?
Go to Step 4.
Replace the seat belt with
pre-tensioner.
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STEP 4. Voltage measurement 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 lap 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 lap pre-tensioner harness side
connector.
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(4)
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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 PA2-,
PA2+, and then release the short spring.
(5)Connect the negative
battery terminal.
(6)Ignition switch: "ON"
(7)Take the measurements
below at the SRS-ECU harness side connector.
- Voltage between PA2-, PA2+
line and body earth
OK: 1 V or less
(8)Disconnect the negative battery
terminal.
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness PA2-,
PA2+
line between the SRS-ECU connector
and the lap pre-tensioner connector.
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STEP 5. Check whether the diagnosis code is set again.
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Q.
Is diagnosis code No. B1628 set?
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Replace SRS-ECU.
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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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