Code No. B1622 Driver’s lap pre-tensioner (squib) system (shorted to
squib circuit power supply)
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If diagnosis code No. B1622 is set in the SRS-ECU, be
sure to diagnose the CAN bus line.
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OPERATION
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).
TROUBLE JUDGEMENT
The code is set when the SRS-ECU lap
pre-tensioner (squib) circuit is shorted to power supply.
PROBABLE CAUSES
- Damaged wiring harness and connector
- 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. B1622 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 the special tool dummy resistor
(MB991865) to the special tool resistor harness (MB991866).
(4)Connect
the special tool resistor harness 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. B1622 set?
Go to Step 4.
Replace the seat belt with
pre-tensioner (Refer to ).
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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 PD2+, PD2- line and the short spring and 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 PD2+, PD2- 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 PD2+,
PD2- 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. B1622 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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