Code No.B1603: Seat belt pre-tensioner (driver’s side) (squib) system (short-circuited between terminals of the squib circuit)




OPERATION



DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Improper engaged connector or defective short spring*
  • Short circuit between the seat belt pre-tensioner (driver’s side) (squib) circuit terminals
  • Damaged connector(s)
  • Malfunction of the SRS-ECU
note *: The squib circuit connectors integrate a "short" spring (which prevents the air bag from deploying unintentionally due to static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, if connector C-155 or D-15 <LHD> or D-23 <RHD> is damaged or improperly engaged, the short spring may not be released when the connector is connected.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code.

Q. Is diagnosis code B1519 set?
Go to Step 2.
Go to Step 3.

STEP 2. Connector lock check: SRS-ECU connector C-155. (M.U.T.-III diagnosis code)
(1)Disconnect the negative battery terminal.

(2)Disconnect the connectors C-155 and then reconnect it.
(3)Connect the negative battery terminal.
(4)Erase the diagnosis code memory, and check the diagnosis code.

Q. Is diagnosis code B1603 set?

Go to Step 3.

The procedure is complete. It is assumed that diagnosis code B1603 set as connector C-155 was engaged improperly.

STEP 3. Connector lock check: SRS-ECU connector C-155 and seat belt pre-tensioner (driver’s side) connector D-15 <LHD> or D-23 <RHD>. (M.U.T.-III diagnosis code)
(1)Disconnect the negative battery terminal.

(2)Disconnect the connectors C-155 and then reconnect them.


(3)Disconnect connector D-15 <LHD> or D-23 <RHD> and then reconnect them. Use a flat-tipped screwdriver to pull out the locking button at the harness side connector.
(4)Connect the negative battery terminal.
(5)Erase the diagnosis code memory, and check the diagnosis code.

Q. Is diagnosis code B1603 set?

Go to Step 4.

The procedure is complete. It is assumed that diagnosis code B1603 set as connector C-155 or D-15 <LHD> or D-23 <RHD> was engaged improperly.

STEP 4. Check the diagnosis code by connecting a dummy resistor. (M.U.T.-III diagnosis code)
(1)Disconnect the negative battery terminal.


(2)Disconnect seat belt pre-tensioner (driver’s side) connector D-15 <LHD> or D-23 <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 D-15 <LHD> or D-23 <RHD> harness side connector.
(5)Connect the negative battery terminal.
(6)Erase diagnosis code memory, and then check the diagnosis code.

Q. Is diagnosis code B1603 set?

Go to Step 5.

Replace the seat belt with pre-tensioner (driver’s side) (Refer to ).

STEP 5. Resistance measurement at the SRS-ECU connector C-155.
(1)Disconnect the negative battery terminal.

(2)Disconnect SRS-ECU connector C-155.


(3)
danger To prevents the seat belt pre-tensioner from operating unintentionally, disconnect the seat belt pre-tensioner (driver’s side) connector D-15 <LHD> or D-23 <RHD> to short the squib circuit.
Disconnect seat belt pre-tensioner (driver’s side) connector D-15 <LHD> or D-23 <RHD>. Use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector.

(4)
caution Insert an insulator such as a cable tie to a depth of 7 mm or more, otherwise the short spring will not be released.
Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 51, 52 and the short spring to 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.
Resistance measurement between C-155 harness side connector terminals 51 and 52
OK: Open circuit

Q. Is the check result normal?

Go to Step 6.

Repair the harness wires between SRS-ECU connector C-155 (terminal No.51 and 52) and the seat belt pre-tensioner (driver’s side) connector D-15 <LHD> or D-23 <RHD> (terminal No.2 and 1)

STEP 6. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1603 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).