Code No.B1632
Driver’s knee air bag module (squib) system (open circuit of squib circuit)
caution
If the diagnosis code B1632
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 open circuit occurs to the SRS-ECU driver’s knee air
bag module (squib) circuit.
PROBABLE CAUSES
Poor contact of connector
Open circuit to driver’s knee air bag module (squib) circuit
Malfunction of SRS-ECU
DIAGNOSIS PROCEDURE
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. B1632 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. Diagnosis check by dummy resistor connection.
(1)Check that the negative battery terminal is disconnected. If the negative battery
terminal is connected, disconnect it.
(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.
(3)Connect the special tool dummy resistor (MB991865) to the 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. B1632 set?
Go to Step 4.
Replace the driver’s knee air bag module (Refer to ).
STEP 4. Resistance measurement at the SRS-ECU connector and the knee
air bag module connector.
(1)Check that the negative battery terminal is disconnected. If the negative battery
terminal is connected, disconnect it.
(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.
(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.
(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)Connect special tool resistor (MB991884) to the removed knee air bag module harness side
connector.
(6)Take the measurements below at the resistor harness and C-126 harness side connector.
Continuity KDS- line between SRS-ECU connector and resistor
harness connector
Continuity KDS+ line between SRS-ECU connector and resistor harness connector
OK: Continuity (less than 2 Ω)
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.
STEP 5. Check whether the diagnosis code is reset.
Q.
Is the diagnosis code No. B1632 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 ).
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
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