Code No.B1605
Seat belt pre-tensioner (driver’s side) (squib) system (short-circuited to the earth)
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 (driver’s
side) (squib) is shorted to earth
PROBABLE CAUSES
Damaged wiring harness and connector
Seat belt pre-tensioner (driver’s side) (squib) harness shorted to earth.
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)Disconnect seat belt pre-tensioner (driver’s side) connector C-18 <LHD> or
C-31 <RHD>. Use a flat-tipped screwdriver to pull out the locking button at
the harness side connector, and then disconnect the connector.
(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884). (4)Connect special tool (MB991884) to the C-18 <LHD> or C-31 <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 B1605 set?
Go to Step 2
Replace the seat belt with pre-tensioner (driver’s side) (Refer to ).
STEP 2. Resistance measurement at the B-111 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-111 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.
Disconnect seat belt pre-tensioner (driver’s side) connector C-18 <LHD> or
C-31 <RHD>. Use a flat-tipped screwdriver to pull out the locking button at
the harness side connector, and then disconnect the 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
51/52 the short spring, and release the short spring. (5)
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-111 harness side connector.
Continuity between terminal No. 51/52 and body
earth
OK: No continuity
Q.
Is the check result normal?
Go to Step 3
Repair the wiring harness between the B-111 SRS-ECU connector terminal No. 51/52
and the C-18 <LHD> or C-31 <RHD> seat belt pre-tensioner connector
(driver’s side) (terminal No.2 and 1).
STEP 3. Check whether the diagnosis code is reset.
Q.
Is diagnosis code B1605 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 (driver’s side) (Refer to 
).)
