Code No.B1633
Driver’s knee air bag module (squib) system (shorted to squib circuit
earth)
caution |
If the diagnosis code B1633
is set to 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 electric
current is supplied from SRS-ECU to the knee air bag module (squib).
TROUBLE JUDGEMENT
The code is set when the SRS-ECU driver’s
knee air bag module (squib) circuit
is shorted to earth.
PROBABLE CAUSES
- Damaged wiring harness and connectors
- Driver’s knee air bag module (squib) harness shorted to
earth
- 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 reset.
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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 the diagnosis code No. B1633 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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![](../../../img/52/AC609126AF00ENG.png)
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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 knee air bag module harness side
connector.
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![](../../../img/52/AC301553DR00ENG.png)
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(3)Connect dummy resistor (MB991865) to special
tool resistor harness (MB991884). (4)Connect the special tool resistor
harness to the knee air bag module 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 the diagnosis code No. B1633 set?
Go to Step 4.
Replace the
driver’s knee air bag module (Refer to ).
Then go to Step 5.
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STEP 4. Resistance 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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![](../../../img/52/AC905015AC00ENG.png)
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(2)While pushing the part "A" indicated in the
figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the lock lever, and
disconnect the SRS-ECU
connector.
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![](../../../img/52/AC609126AF00ENG.png)
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(3)
danger |
To release the SRS-ECU connector short spring in
the following
operations, disconnect this harness side 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 knee air bag module harness side
connector.
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![](../../../img/52/AC905150AR00ENG.png)
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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 KDS-,
KDS+ line and the short spring, and release the short
spring. (5)Take the measurements below at the SRS-ECU harness side
connector.
- Continuity between KDS-, KDS+ line and body
earth
OK: No continuity
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness KDS-,
KDS+ line between the SRS-ECU connector
and the knee air bag module connector.
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STEP 5. Check whether the diagnosis code is reset.
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Q.
Is the diagnosis code No. B1633 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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