Code No. B1612:
Seat belt pre-tensioner (passenger’s side) (squib) system (shorted to
squib circuit power
supply)
caution |
If diagnosis code No.
B1612 is set in the 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 seat belt pre-tensioner (squib).
TROUBLE JUDGEMENT
The code is set when the input terminal of
SRS-ECU seat belt pre-tensioner (passenger’s
side) (squib) is shorted to power supply.
PROBABLE CAUSES
- Damaged wiring harness and connector
- Seat belt pre-tensioner (passenger’s side) (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. B1612 set?
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Go to Step 3.
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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/ACB04317AB00ENG.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 seat belt pre-tensioner
(passenger’s side) harness
side connector.
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![](../../../img/52/AC301553DP00ENG.png)
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(3)Connect special tool dummy resistor
(MB991865) to special tool resistor harness (MB991884). (4)Connect
special tool resistor harness to the seat belt pre-tensioner
(passenger’s
side) 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. B1612 set?
Go to Step 4.
Replace the seat belt with
pre-tensioner (passenger’s side).
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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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![](../../../img/52/ACB04317AB00ENG.png)
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(3)
danger |
To release the SRS-ECU connector short spring in
the following
operations, disconnect this seat belt 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 seat belt pre-tensioner
(passenger’s side) harness
side connector.
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![](../../../img/52/ACE02056AO00ENG.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 PTA+,
PTA- 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 PTA+, PTA- 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 PTA+,
PTA- line between the SRS-ECU connector
and the seat belt pre-tensioner (passenger’s side)
connector.
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STEP 5. Check whether the diagnosis code is set again.
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Q.
Is diagnosis code No. B1612 set?
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Replace SRS-ECU.
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Intermittent malfunction.
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