Code No.B1612
Seat belt pre-tensioner (passenger’s side) (squib) system (short-circuited to the power
supply)
OPERATION
Only when the frontal impact exceeding the threshold is simultaneously detected (turned
ON) by the front impact sensor as well as by the analog G-sensor and safing 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
DIAGNOSIS PROCEDURE
STEP 1. Diagnosis check by dummy resistor connection.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative
auxiliary 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 C-31 <LHD> and C-18 <RHD> harness side connector.
(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884). (4)Connect the special tool resistor harness to the C-31 <LHD> and C-18 <RHD>
harness side connector. (5)Connect the negative auxiliary battery terminal. (6)After erasing the diagnosis code memory, check the diagnosis code again. (7)Disconnect the negative auxiliary battery terminal.
Q.
Is diagnosis code B1612 set?
Go to Step 2
Replace the seat belt with pre-tensioner (passenger’s side) (Refer to ).
STEP 2. Voltage measurement at the B-113 SRS-ECU connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative
auxiliary battery terminal is connected, disconnect it.
(2)Disconnect the B-113 SRS-ECU connector.
(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.
Use the flat-tipped screwdriver to pull out the locking button of harness side connector.
After releasing the lock, disconnect the C-31 <LHD> and C-18 <RHD> 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 terminal
5/6, and the short spring, and release the short spring. (5)Connect the negative auxiliary battery terminal. (6)Electric motor switch to the "ON" position. (7)
caution
Do not insert a test probe into the terminal from its front side directly
as the connector contact pressure may be weakened.
Take the measurements below at the B-113 harness side connector.
Voltage between terminal No. 5/6 and body earth
OK: 1 V or less (8)Disconnect the negative auxiliary battery terminal.
Q.
Is the check result normal?
Go to Step 3
Repair the harness wires between SRS-ECU connector B-113 (terminal No.5 and 6)
and the seat belt pre-tensioner (passenger’s side) connector C-31 <LHD> and C-18 <RHD>
(terminal No.1 and 2)
STEP 3. Check whether the diagnosis code is reset.
Q.
Is diagnosis code B1612 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with
Intermittent Malfunction ).
)
)
)
)
)
)
)
Go to Step 2
Replace the seat belt with pre-tensioner (passenger’s side) (Refer to 
).)
