[ Pobierz całość w formacie PDF ]

output is to signal the BCM/ETAC module in the vehicle to unlock the vehicle doors. If a crash
output signal is in progress, a second crash output signal will not be sent unless the first one is
completed.
The ACU doesn t perform diagnostics on the crash output function. In addition, the failure
handlings such as circuit failure between ACU and BCM, noise injection in crash output command
line that may induce invalid message shall be handled by BCM not ACU
14
Chonan Technical Service Training Center
SRS
Crash Output Signal
Crash Output interface to the ACU
6. System Diagnostics and Fault Handling
6.1 Fault Recognition
The ACU shall start the fault management during the prove-out period. The ACU qualifies a fault
when it has detected that fault for the qualification period or number of occurrences. The ACU shall
store the fault codes onto EEPROM and turn ON the SRS warning lamp. RAS sensor fault are tested
at a more rapid rate than other faults ; their sample rate is based on the algorithm update rate. Some
internal fault are only tested during phase-up.
After a fault is qualified, the fault is de-qualified when that fault has been not detected for the de-
qualification period. If no qualified faults are present, the warning lamp turns off. Diagnosis of firing
devices is suspended during the deployment process, but resumes thereafter. Faults for devices
which were fired in a crash will be suppressed.
15
Chonan Technical Service Training Center
SRS
6.2 Fault Handling
An internal fault is a fault inside of the ACU (i.e. accelerometer, microcomputer power supply, or
watch dog),and is not erasable. An external fault is a fault outside of the ACU (i.e. RAS II, Occupant
Detection, squibs), and is erasable. Once any internal fault has been qualified, the corresponding fault
record in non-volatile memory of the ACU shall not be erasable. All internal faults shall not de-qualify.
The ACU denounces all faults to make sure that no erroneous faults are recorded. The ACU shall
set qualified faults to historic faults as soon as the active fault conditions are recovered and
disqualified. At this time, the warning lamp shall be turned off and historic fault code and
corresponding fault information shall be stored in EEPROM within the ACU.
16
Chonan Technical Service Training Center [ Pobierz całość w formacie PDF ]