- Inspection for indicating light of safety airbag
(1) When set the ignition switch at ON position, confirm whether the indicating light illuminates.
(2) After illuminating for five seconds, confirm whether indicating light extinguishes forever.
(3) If starting ignition switch for five seconds, indicating light does not extinguish (flash or illuminate for long
time), confirm the position of system malfunction with special diagnostic tool according to the flash
situation of indicating light. - System diagnosis
Safety airbag controller (KD4.1) will implement a series of cycle diagnostic testing to check whether the
function of airbag system has been prepared completely. This test will prevent restraint system from
exploding wrongly and insure the necessary explosion in impact. If finding any malfunction, safety airbag
controller (KD4.1) will store a applicable malfunction code and turn on indicating light to indicate a mal-
function state to be easy to maintain. - Malfunction judgment
(1) Malfunction category
System malfunction could be divided into three categories: power supply malfunction, subassembly
assembling malfunction and ECU inner malfunction.
a. Power supply malfunction
Normal working voltage of ECU is 9-18 V, related working voltage is 12 V. When automobile key is
turned to ACC gear, ECU connects power and begins to self-check, indicating light extinguishes
after illuminating for five seconds, this shows there is not any malfunction in ECU and exterior
subassembly, they could work normally. When automobile power voltage is less than 9V or higher
than 18V, ECU will self-check again. If self-checking could pass, ECU works normally, and indicat-
ing light extinguishes; if self-checking could not pass, it is necessary to self-check again, this self-
checking could be made six times, if indicating light illuminates all the time after six times, there is
some malfunction in power supply.
b. Assembling malfunction of airbag subassembly
Assembling malfunction of airbag subassembly is that malfunction which only needs to change or
repair airbag subassembly without needing to change ECU, including the situation that airbag
subassembly is not connected completely. If happening this malfunction when connecting power
supply, indicating light will flash N times at first, then it will illuminate all the time until malfunction is
removed. If happening impact in malfunction term, ECU could explode the channel of good part
and record every malfunction when exploding.
c. Inner malfunction of controller
Inner malfunction is the malfunction happening in ECU body, when happening this malfunction,
ECU could not explode airbag, and will record the impacting acceleration.
Note: common repairer could not repair this inner malfunction, if happening this malfunction,
it is necessary to change ECU.
(2) Malfunction state display
Malfunction treatment.........................................
- Basic procedure of malfunction diagnosis
z After assembling new electronic control unit of safety airbag system, indicating light of safety airbag
system will extinguish forever after flashing for 5 seconds when ignition switch is at state of ON, this
shows airbag system works normally. At this time, the system does not need to repair, it is necessary
to make system diagnosis and repair when showing any situation except this.
z If indicating light of safety airbag system does not illuminate when ignition switch is at the state of ON,
check the related circuits of indicating light, then operate it to make it enter working state.
Supplemental restraint system--Malfunction treatment244
Warning light illuminate Scanning ECU by connecting Find the malfunction Deal with Clean the code
and does not extinguish diagnostic instrument malfunction