Code No.B1631
Driver’s knee air bag module (squib) system (short circuit
between squib circuit terminals)
caution |
If the diagnosis code B1631
is set to SRS-ECU, be sure to diagnose the CAN bus
line.
|
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 short circuit
occurs to between the terminals of SRS-ECU knee
air bag module (squib) circuit.
PROBABLE CAUSES
- Damaged short spring *
- Short circuit between terminals of knee air bag module (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
air bags 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.
|
|
STEP 1. M.U.T.-III CAN bus diagnostics.
|
|
Use M.U.T.-III to diagnose the CAN
bus lines.
|
|
Q.
Is the check result normal?
|
|
Go to Step
2.
|
|
|
|
Repair the CAN bus
line (Refer to GROUP 54C - Troubleshooting ).
|
|
|
|
STEP 2. Check whether the diagnosis code is
reset.
|
|
(1)Connect the negative battery terminal.
|
|
(2)After erasing the diagnosis code memory, check
the diagnosis code again.
|
|
(3)Disconnect the negative battery
terminal.
|
|
Q.
Is the diagnosis code No. B1631 set?
|
|
Go to Step
3.
|
|
|
|
Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunction ).
|
|
|
|
STEP 3. Connector check: SRS-ECU, knee air bag
module.
|
|
(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
|
![](../../../img/52/AC905015AC00ENG.png)
|
(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. After disconnecting the
SRS-ECU connector, connect it again.
|
![](../../../img/52/AC609126AF00ENG.png)
|
(3) After disconnecting the knee
air bag module harness side connector, connect the connector
again. For the knee air bag module 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 the diagnosis code No. B1631 set?
Go to Step
4.
Replace
the connector concerned.
|
|
STEP 4. Diagnosis check by dummy resistor
connection.
|
|
(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
|
![](../../../img/52/AC609126AF00ENG.png)
|
(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.
|
![](../../../img/52/AC301553DR00ENG.png)
|
(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991884). (4)Connect the 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. B1631 set?
Go to Step
5.
Replace
the driver’s knee air bag module (Refer to ).
|
|
STEP 5. Resistance check at the SRS-ECU
connector.
|
|
(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
|
![](../../../img/52/AC905015AC00ENG.png)
|
(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.
|
![](../../../img/52/AC609126AF00ENG.png)
|
(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.
|
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.
|
![](../../../img/52/AC905150AR00ENG.png)
|
(4)
caution |
The short spring may not be
released due to the insufficient insertion.
Therefore, insert
the insulator for 4 mm or more.
|
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
OK: No continuity
Q.
Is the check result normal?
Go to Step
6.
Repair
the wiring harness KDS-, KDS+ line between the SRS-ECU
connector
and the knee air bag module connector.
|
|
STEP 6. Check whether the diagnosis code is
reset.
|
|
Q.
Is the diagnosis code No. B1631 set?
|
|
Replace SRS-ECU
(Refer to ).
|
|
|
|
Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunction ).
|
|
|