SRS-ECU


The SRS-ECU incorporates an analogue G-sensor and safing G-sensor for frontal collisions and a safing G-sensor for side collisions.
In frontal collisions, the driver’s and front passenger’s air bags deploy only when both the analogue and safing G-sensors detect simultaneously a collision-induced G of criteria as in the case with the conventional system.
In side collisions, the side and curtain air bags on the side subjected to an impact deploys if the side impact sensors and the SRS-ECU safing G-sensor detect simultaneously lateral G forces above criteria.
The SRS-ECU is provided with the following capabilities:

caution Never disassemble the SRS-ECU.

DIAGNOSIS FUNCTION


The SRS-ECU has the following functions to make system check using M.U.T.-III easy.

DIAGNOSIS CODE SET


The SRS-ECU diagnoses the following items and stores a diagnosis code in the non-volatile memory (EEPROM*1) when a problem is detected. Therefore, the memory is not deleted after a battery terminal is disconnected. (The diagnosis code memory can be deleted by the M.U.T.-III).
Code No.
 Major contents of diagnostics
B1400*3
 Driver’s air bag module (squib) short-circuited
B1401*3
 Driver’s air bag module (squib) open-circuited
B1402*3
 Driver’s air bag module (squib) drive circuit (earth side) short-circuited
B1403*3
 Driver’s air bag module (squib) drive circuit (power supply side) short-circuited
B1405*4
 Driver’s air bag module (squib) activating circuit open-circuited
B1406*4
 G-sensor of front impact sensor (RH) failure
B1407*3
 Front impact sensor (RH) voltage error
B1408*3
 Front impact sensor (RH) communication error
B1409*3
 Front impact sensor (RH) communication impossible
B1410*3
 Passenger’s (front) air bag module (squib) short-circuited
B1411*3
 Passenger’s (front) air bag module (squib) open-circuited
B1412*3
 Passenger’s (front) air bag module (squib) drive circuit (earth side) short-circuited
B1413*3
 Passenger’s (front) air bag module (squib) drive circuit (power supply side) short-circuited
B1415*4
 Passenger’s (front) air bag module (squib) activating circuit open-circuited
B1416*4
 G-sensor of front impact sensor (LH) failure
B1417*3
 Front impact sensor (LH) voltage error
B1418*3
 Front impact sensor (LH) communication error
B1419*3
 Front impact sensor (LH) communication impossible
B1420*3
 Side-airbag module (RH) (squib) short-circuited
B1421*3
 Side-airbag module (RH) (squib) open-circuited
B1422*3
 Side-airbag module (RH) (squib) drive circuit (earth side) shorted
B1423*3
 Side-airbag module (RH) (squib) drive circuit (power supply side) shorted
B1425*4
 Side-airbag module (RH) (squib) activating circuit open-circuited
B1426*4
 G-sensor of side impact sensor (RH) failure
B1427*3
 Side impact sensor (RH) voltage error
B1428*3
 Side impact sensor (RH) communication error
B1429*3
 Side impact sensor (RH) communication impossible
B1430*3
 Side-airbag module (LH) (squib) short-circuited
B1431*3
 Side-airbag module (LH) (squib) open-circuited
B1432*3
 Side-airbag module (LH) (squib) drive circuit (earth side) shorted
B1433*3
 Side-airbag module (LH) (squib) drive circuit (power supply side) shorted
B1435*4
 Side-airbag module (LH) (squib) activating circuit open-circuited
B1436*4
 G-sensor of side impact sensor (LH) failure
B1437*3
 Side impact sensor (LH) voltage error
B1438*3
 Side impact sensor (LH) communication error
B1439*3
 Side impact sensor (LH) communication impossible
B1440*3
 Curtain air bag module (RH) (squib) short-circuited
B1441*3
 Curtain air bag module (RH) (squib) open-circuited
B1442*3
 Curtain air bag module (RH) (squib) drive circuit (earth side) shorted
B1443*3
 Curtain air bag module (RH) (squib) drive circuit (power supply side) shorted
B1445*4
 Curtain air bag module (RH) (squib) activating circuit open-circuited
B1450*3
 Curtain air bag module (LH) (squib) short-circuited
B1451*3
 Curtain air bag module (LH) (squib) open-circuited
B1452*3
 Curtain air bag module (LH) (squib) drive circuit (earth side) shorted
B1453*3
 Curtain air bag module (LH) (squib) drive circuit (power supply side) shorted
B1455*4
 Curtain air bag module (LH) (squib) activating circuit open-circuited
B1460*3
 Seat belt pre-tensioner (RH) squib short-circuited
B1461*3
 Seat belt pre-tensioner (RH) squib open-circuited
B1462*3
 Seat belt pre-tensioner (RH) squib (earth side) short-circuited
B1463*3
 Seat belt pre-tensioner (RH) squib (power supply side) short-circuited
B1465*4
 Seat belt pre-tensioner (RH) activating circuit open-circuited
B1466*4
 Analogue G-sensor malfunction
B1467*4
 Safing G-sensor open-circuited (for frontal collision)
B1469*4
 Safing G-sensor malfunction (for side collision)
B1470*3
 Seat belt pre-tensioner (LH) squib short-circuited
B1471*3
 Seat belt pre-tensioner (LH) squib open-circuited
B1472*3
 Seat belt pre-tensioner (LH) squib drive circuit (earth side) short-circuited
B1473*3
 Seat belt pre-tensioner (LH) squib drive circuit (power supply side) short-circuited
B1475*4
 Seat belt pre-tensioner (LH) activating circuit open-circuited
B1476*2
 Power supply voltage (IG1 (A) voltage) drops abnormally.
B1477*2
 Power supply voltage (IG1 (B) voltage) drops abnormally.
B1478*4
 SRS-ECU capacitor circuit voltage too high
B1479*4
 SRS-ECU capacitor circuit voltage too low
B1496*4
 SRS-ECU non-volatile memory (EEPROM*1)
B1497*4
 SRS-ECU ASIC (for frontal activation)
B1498*4
 SRS-ECU ROM or RAM
B1499*4
 Collision Decision
B1509*2
 Incorrect SRS-ECU
B1582
 Front impact sensor (RH) ID fault
B1583
 Front impact sensor (LH) ID fault
B1584
 Side impact sensor (RH) ID fault
B1585
 Side impact sensor (LH) ID fault
B1588*4
 SRS-ECU up converter unit
B1589*4
 SRS-ECU down converter unit
B1590*4
 SRS-ECU ER capacitance big
B1591*4
 SRS-ECU ER capacitance small
B1592*4
 SRS-ECU front air bag analog G-sensor failure
B1593
 SRS-ECU noise fault
B1594*4
 SRS-ECU ASIC (for side activation)
U1073*2
 Bus-off
note
  • *1: Electrically Erasable Programmable ROM
  • *2: This diagnosis code will remain in memory and the SRS warning lamp will be switched off when the system returns to normal condition.
  • *3: This diagnosis code will remain in memory and the SRS warning lamp will be switched on even if the system returns to normal condition.
  • *4: This diagnosis code can not be erased by "Erase diagnosis codes" function.

DATA LIST OUTPUT


The data input from all sensors and switches can be read using the M.U.T.-III.
No.
 Data list item
 Check condition
 Normal condition
01
 Failure continuation time 1
 Always
 Maximum time to be stored: 9999 minutes (approximately seven days)
02
 Failure continuation time 2
 Always
10
 Elimination times
 Always
 Maximum time to be stored: 250 times

ACTUATOR TEST


The M.U.T.-III can be used to forcibly operate the next actuator.
M.U.T.-III display
 Item No.
 Item
 Parts to be activated
SRS Warning Lamp
 01
 The SRS warning lamp illuminates.
 Combination meter output