Objectives - To understand on System Network - Operation of Each components - Diagnosis - Diagnostic trouble codes - Troubleshooting - Customer Satisfaction
Cautions General cautions before or during the service for SRS The diagnosis and troubleshooting for SRS should be performed by authorized technician.
Cautions Failure to carry out service operations in the correct sequence could cause the airbag system to unexpectedly deploy during servicing, possibly leading to a serious injury. In addition, if a mistake is made in servicing the airbag system, it is possible that the airbag may fail to operate when required. Before performing servicing (including removal or installation of components, inspection or replacement), be sure to read the following items carefully. Be sure to proceed airbag related service longer than approx. 30 seconds from the time the the ignition switch is turned to the LOCK position and the battery negative (-) terminal cable must be disconnected from the battery. The airbag system is equipped with a back-up power source to assure the deployment of airbag when the battery cable is disconnected by an accident. The back-up power is available for approx. 150ms. 30 seconds
When the battery negative (-) terminal cable is disconnected from the battery, memory of the digital clock and audio system can be canceled. So before starting work, make a record of the contents memorized by the audio memory system. After the service work is finished, reset the audio system and adjust the digital clock. Malfunction symptoms of the airbag system are difficult to confirm, so the diagnostic trouble codes (DTC) become the most important source of information when troubleshooting. When troubleshooting the airbag system, always read out the diagnostic trouble codes using Hi-Scan before disconnecting the battery negative (-) terminal. Cautions
Any part of airbag system has been dropped, or if there are cracks, dents or other defects in the case, bracket or connector, replace them with new ones. Never use any airbag part from another vehicle (model). When replacing parts, replace them with new parts. Never attempt to disassemble and repair the airbag modules (DAB, PAB, FSAB) and BPT, clock spring (contact coil) and wiring harness in order to reuse them. After service work for the airbag system is completed, perform the SRS SRI (Service reminder indicator) check. The airbag indicator (SRS SRI) lamp can be interrupted by other circuit fault in some cases. Therefore if the airbag indicator lamp comes on, be sure to erase the DTC using Hi-Scan just after repairing or replacing the troubled part(s) including fuse(s) Cautions
Functions Of Airbag Absorbs kinematics energy of occupants. Protects occupants from interior trims. Protects occupants from broken glass. Reduces occupants neck load by kinematically restraining spin of neck.
Application ACU version: AB8-E ProjectTypeEngineHMC Part No.Delphi Part No.Bosch Part No. Advanced 1GAS E100SA * 2GAS E000SA * Depowered 3 GAS DSL E E700 SA SA * * 4 GAS DSL E E600 SA SA * * 5 GAS DSL E E500 SA SA * * FIS(200G) E000SA SIS(50G) E000SA Regarding type 3,4,5, if diesel engine vehicles are necessary to develop separately from gasoline engine, JM ACU needs 3 connector additionally. Bosch standard FIS (UFS1 named by Bosch) and SIS (PAS3 named by Bosch) are used in this program.
AdvancedPowered Type-1Type-2Type-3Type-4Type-5 Firing Loops Airbag Driver 1 st & 2 nd stage22111 Airbag Pass. 1 st & 2 nd stage2211- Front Belt pretensioners22222 Front Retractor pretensioner22222 Front Side Airbag2-2-- Rear Side Airbag----- Curtain Airbag2-2-- Input Buckle Switch22--- Seat Track Position Sensor22--- Front Impact Sensor (FIS)22222 Side Impact Sensor2-2-- PODS for frontal passenger11--- Output Warning Lamp11111 Passenger Telltale Lamp11--- Crash Output11111 Configuration Matrix
2 Stage PAB PODS Sear Track Position Sensor ACU Advanced 2 Stage DAB Buckle Pretensioner TELLTALE PASSENGER AIRBAG OFF Seat Belt Pretensioner System Overview Crash sensor
Components and Functions ACU: Airbag Control Unit FIS: Front Impact Sensor SIS: Side Impact Sensor DAB: Driver Airbag PAB: Passenger Airbag FSAB: Front Side Airbag CAB: Curtain Airbag POD: Passenger Occupant Detector STPS: Seat Track Position Sensor
Major Components - - ACU: Airbag Control Unit - - FIS: Front Impact Sensor - - SIS: Side Impact Sensor - - DAB: Driver Airbag – 2 stages squib - PAB: Passenger Airbag - 2 stages squib - - FSAB: Front Side Airbag - CAB: Curtain Airbag - - PODS: Passenger Occupant Detection Sensor - SPT: Seatbelt Pretensioner - - BPT: Buckle Pretensioner - STPS: Seat Track Position Sensor
Airbag Deployment 105m Sec Vent Gas (Bag Deflation) Airbag System Completed 20m Sec35m Sec40m Sec Bag Deploying Ignite the Inflator Full Deployment of the Bag Produce Nitrogen Gas to Inflate the Bag Protect the Occupants AIRBAG SYSTEM OPERATING SEQUENCE 3m Sec Crash Crash Sensing
SRS – Dual Stage A/Bag STPS : Seat Track Position Sensor - - 5% dummy - - Low pressure deploy Low pressure deploy Less than 5 Click Seat position Crash speed S/belt fasten or not 12mph 9mph Belt pre-tensioner deploy No deploy
SRS – Dual Stage A/Bag STPS : Seat Track Position Sensor % dummy - - Low or High pressure deploy depends on the crash speed and seat belt fasten or not. 12mph 18mph 22mph 26mph 15mph More than 5 Click Less than 5 Click S/belt fasten or not No deploy Seat position Crash speed Seat belt fasten No seat belt fasten Low pressure deploy LowHigh LowHigh
ACU Location On the longitudinal center line, under the centerfacia assembly
ACU Internal Functions DC/DC Converter: The DC/DC converters of the power supply (ASIC) includes a step up and step down converter for the energy reserve which provides the firing current for the applied firing circuits and the internal operation voltage (Vcc) of the ACU. If the internal operating voltage falls below a defined threshold a reset is executed. Watchdog: The watchdog (ASIC) cyclically checks the micro controller. In case of a fault the micro controller will be reset and the firing loops will be active locked. The warning lamp is turned on. X/-X/Y Acceleration Sensor: The integrated electrical accelerometer provides an electrical representation of the vehicles acceleration along X/-X and Y axis. The electrical signals are proportional to the acceleration. Those signals are evaluated by the micro controller via A/D converter. The firing threshold is adjustable by parameter setting for the corresponding algorithm. If the adjusted threshold is exceeded, the ACU will drive the high side and low side transistors of the appropriate firing loops. Full Electronic Concept: The ACU is designed under a full electronic concept. Therefore no mechanical safing sensor (a trigger switch or a safing switch) exists.
ACU Internal Functions Firing Loops 1 st Stage Front Airbags: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both stages of the front airbags are fired out of the energy reserve capacitors. Firing Loops 2 nd Stage Front Airbags: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both stages of the front airbags are fired out of the energy reserve capacitors. / In the event of a first stage deployment it will be necessary to deploy the second stage of both frontal airbags after the crash at a safe time. This disposal time is TBD for passenger after the first stage has been deployed. Firing Loops Buckle Belt Pretensioners: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both of the front buckle belt pretensioners are fired out of the battery. Firing Loops Retractor Pretensioners: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both of the front Retractor pretensioners are fired out of the battery.
ACU Internal Functions Firing Loops Side Airbags: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both of the front side airbags are fired out of the energy reserve capacitors. Firing Loops Curtain Airbags: Each firing loop consists of a high side and low side switch. The current is limited by the ASIC to 1.2-3A. Both of the front curtain airbags are fired out of the energy reserve capacitors. Energy Reserve and Backup Time: The ACU has energy reserve that ensures the internal operation of the ACU and firing circuits for 150ms after loss of battery power.
FIS (Front Impact Sensor) Generally it is difficult to get and detect the crash data in case of slope or pole road and offset crash condition. FIS lets SRSCM decide early the firing time and prevents the firing delay.
The ACU shall change seat buckle status in accordance with following diagram. Seat Belt Buckle Operation
Deployment Logic for Seat Buckle status Seat Buckle StatusPretension Deployment Belted PT Unbelted NPT Faults PT ACU shall monitor seat buckle status every 200ms. If the ACU detected fault status 10 consecutive time, then the warning lamp turn on and fault is qualified. After the fault qualified, if ACU detected no fault status 20 consecutive time, then warning lamp turn off and fault is de-qualified. Fault qualification time : 200ms 10 consecutive = 2 sec Fault de-qualification time: 200ms 20 consecutive = 4 sec
PODS-B ECU SHUNT BAR STPS (SEAT TRACK POSITION SENSOR) PRESSURE SENSOR BLADDER Passenger Occupant Detection
Seat Track Position Sensor System Default Status ACU shall be defined the enable condition and allowed deployment during the system initialization. Fault qualification and de-qualification ACU shall monitored seat track position sensor status every 200ms. If the ACU detected fault status 10 consecutive times, then the warning lamp turn on and fault is qualified. After the fault qualified, if ACU detected no fault status 20 consecutive time, then warning lamp turn off and fault is de- qualified. Fault qualification time : 200ms 10 consecutive = 2 sec Fault de-qualification time: 200ms 20 consecutive = 4 sec
Fault Qualification - Kinds of Fault. Active Fault. Active Fault. Historic Fault. Historic Fault. Historical Fault. Historical Fault
The ACU shall qualify the fault when it has detected that fault 10 times in succession during the system monitoring tests. The ACU shall store the fault codes into EEPROM and turn on the warning lamp. The diagnostic test cycle for fault detection is 200ms, so the time for a particular fault condition to be detected by the ACU is approximately 2sec(=200ms X 10) for fault qualification. If a fault has qualified and maintained the fault condition, the warning lamp shall be turned on. This status is called Active Fault. After a fault is qualified once, the fault shall be disqualified when that fault has disappeared for 20 diagnostic test cycles (i.e. 4sec, i.e. 200ms X 20) in succession. In this case the warning lamp shall turn off and this status is called Historical Fault. 1) Active Fault: In order to be qualified as a fault, the ACU shall detect that fault 10 times in succession. If the measurement value is considered as a fault per one cycle, the fault counter shall be increased to the value corresponding to the particular fault. When the fault counter reaches a constant value(corresponding to 2 seconds), then the fault is qualified and warning lamp shall be turned on. 2) Historical Fault: When the fault disappears, the fault counter is decreased by 1. If the decreased fault counter is below or equal to the value corresponding to the particular fault(at least 10 seconds), that fault shall become a history fault and the warning lamp shall be turned off. Fault Recognition
Exception 1) Fault handling for "Vbatt Too Low / High" is different from other faults. When the battery voltage is too low for 10 seconds, the warning lamp turns on. Ten seconds after the battery voltage becomes normal, this fault is stored in EEPROM as a historical fault, and then the warning lamp turns off. This procedure shall be repeated if that fault re-appears. Exception 2) For internal fault, the fault qualification procedure is the same to other external faults However fault erase is not permitted. The ACU shall be replaced in this case. Exception 3) Generally the warning lamp shall be turned off for the external fault when that fault disappears. If the sum of the external faults are greater than or equal to 10, the warning lamp shall turn on continuously. The Vbatt Too Low fault is an exception for this condition. Exception 4) The fault handling for Occupant Classification system is different from other faults. When the ACU receives 2 consecutive fault message from PODS-B ECU, the warning lamp shall turn on. After 4 consecutive no fault messages are received from PODS-B ECU, the warning lamp shall be turned off and the fault shall be stored into the EEPROM as a historical fault. This procedure shall be repeated if that fault appears.
Fault ItemFault Qualification Time Fault Dequalification Time External Fault 2 seconds4seconds Internal Fault2 seconds ( dequalification not permitted ) V batt too Low/High10 seconds Occupant Classification2 seconds4 seconds Fault Qualification
Fault Qualification (External fault) Fault counter xx 1sec 200ms 2s Fault initial detection Active fault determine (Qualified) De-qualified) Fault disappears SRI ON 4s Time SRI OFF The warning Lamp is continuously turned on when the sum of external fault is equal or greater than 10except Vbatt Too Low.
ACU Performance during Active Fault Condition If a fault is detected in either an electronic accelerometer or in the microprocessor, the ACU shall inhibit airbag deployment to minimize the risk of an inadvertent deployment. Under all other fault conditions, the ACU shall attempt to deploy the specific inflatable restraints according to the crash conditions and firing control logic despite the fault. Fault Recording (Storage of the Fault Code) When a fault has been qualified, the ACU shall store in non-volatile memory of the microprocessor the corresponding fault code, Fault time duration and the number of occurrences. The ACU shall be able to store maximum of 10 external faults, 1 internal fault, Vbatt too low fault and 4crash recorded which including the PT only deployment. ACU shall record the earliest 10 external different fault code in the memory. After recording a maximum of 16 fault codes that ACU shall no longer record fault codes. As the crash DTC shall not be disqualified, the number of occurrences shall not be incremented. In case of PT only deployment below 6 times, the fault memory shall be cleared before ACU reuse. Fault Handling
Self-diagnostic and Fault recording after crash event After crash, the ACU shall continuously diagnose both internal and external devices even if any squib was deployed. The fault memory shall continuously update but crash recording shall be frozen at the time of crash. Clear Fault Code When the ACU receives the appropriate command via the serial interface from the diagnostic tester (Hi-SCAN TM ), the fault area in the EEPROM shall be cleared. However, if an internal fault code is logged or if a crash is recorded in the crash entry, the fault clearing should not be happened. Fault Handling
Fault Indication on Historical fault conditions If maximum storage number of external faults are reached and no additionally qualified fault(s) is(are) to be stored in non-volatile memory of the ACU, the ACU should turn the airbag warning lamp ON continuously regardless of the presence of Active fault(s). In addition, if the occurrence number of a certain faults reaches the value 10, the ACU shall turn the airbag warning lamp ON continuously regardless of presence of Active fault(s). In case of initial start-up phase, the ACU shall activate the warning lamp. Fault Indication A fault indicated by the warning lamp shall be illuminated as soon as it has been qualified. The indication shall be off if the external fault is historic. The indicator shall be on when the number of occurrence of historical external fault is greater than or equal to 10 even though the fault has disappeared. However, "Vbatt Too Low" shall be excluded in calculating the sum. Reset active or historic faults shall be reset only by service personal. Internal faults of the ACU or the fault Crash Recorded cannot be reset, and the ACU shall be replaced. SRS Activation
SRS Activation - Case 1 Case 1: Normal or less than 10 Historical faults As soon as the operating voltage is applied to the ACU ignition input, the ACU activates the warning lamp for a bulb check. The lamp shall turn on for 6 seconds during the initialization phase and be turned off afterward. No active fault or number of occurrence of a same historical fault in memory is less than 10 or number of historical faults are less than 10 in its non- volatile memory
The warning lamp continuously turns on for 6 seconds after ignition on and off for 1 second and turn on continuously when the active fault(s) is(are) qualified(crash entry is also one of the active faults that is not erasable) or historic fault conditions are met. SRS Activation - Case 2 Case 2: Active fault including crash entry or Historic fault
There are certain fault conditions in which the microprocessor cannot function and thus cannot control the operation of the standard warning lamp. In these cases, the standard warning lamp shall be directly activated by appropriate circuitry that operates independently of the microprocessor. These cases are: * If a loss of battery supply to the ACU: the warning lamp shall be turned on continuously. * If a loss of internal operating voltage : the warning lamp shall be turned on continuously. * If a reset by the Watchdog Trigger failure occurs : the warning lamp shall be flashed or turned on continuously. * If a loss of microprocessor operation : the warning lamp shall be turned on continuously. * If the ACU is not connected : the warning lamp shall be turned on continuously through the shorting bar. Microprocessor-Independent SRI Activation
Passenger Telltale Indicator As soon as proper operating voltage is applied to ACU ignition input, the ACU shall activate the indicator for an LED check. The LED lamp shall turn on for 4 seconds and turn off for 3 secconds during the initialization phase and be turned off afterward until receive first valid suppression message from PODS system. Indicator Check
Passenger Telltale Indicator Operation This passenger telltale lamp shall display the passenger airbag enable and disable status based on occupant status of passenger seat. The ACU shall receive occupant status information from PODS-B at 1-second intervals during the normal operation period. PODS-B shall send an indeterminate status to the ACU as a default setting for passenger airbag deployment during the prove-out period. The warning lamp shall not turn on base on indeterminate status along but it shall turn on base on the PODS fault information. The telltale lamp shall turn on base on the indeterminate status. After crash if PODS gets reset and sends the indeterminate status, the telltale lamp shall be ON as long as the occupant status is in the indeterminate status.
Occupant status Passenger Telltale lamp Seat emptyON Seat occupied with a small occupantON Seat occupied with a large occupantOFF Indeterminate status ON Passenger Telltale Indicator Operation PODS-B ECU shall send 4 different occupant status information reports shown below via the HS-CAN communication line to the ACU. Then the ACU shall control the passenger Telltale lamp based on this following passenger status information. Once the ACU receives passenger Airbag Deployment Allowed Message from PODS-B, the ACU shall turn off the passenger telltale lamp until it receives the passenger airbag inhibited message.
Electrical Interface for Passenger Telltale Lamp Passenger Telltale Indicator The passenger telltale lamp driver is a power switch to GND and has following characteristics. Interfacing Current: V on max = I on max = 110mA Quiescent Current Lamp off:I leak max = 150uA 12V, 0.22W/LED 4 LED array
PODS-B System Default Status PODS-B ECU shall send indeterminate status via the HI-CAN communication line to the ACU during the system initialization period. Once PODS system stabilized, PODS-B ECU shall send 3 different faults, PODS-B ECU failure, BTS failure, bladder sensor failure, via the HS-CAN communication line to the ACU if PODS-B ECU qualified failure conditions. Fault qualification and de-qualification PODS-B ECU shall send status information via the HS-CAN communication line to the ACU every 1 second. If the ACU received fault status 2 consecutive time, then ACU shall turn on the airbag warning lamp and fault is qualified. After the fault qualified, if ACU received no fault status 4 consecutive time, then ACU shall turn off the airbag warning lamp and fault is de-qualified. Fault qualification time: 1 sec 2 consecutive = 2 sec Fault de-qualification time: 1 sec 4 consecutive = 4 sec
PODS-B PODS Reset After Crash After the Crash event information is sent to the PODS ECU, the ACU should start a 6 seconds counter and should discard the indeterminate status message without any PODS Fault data during this 6 seconds period. Other valid occupant status message should be accepted for change during those 6 seconds interval. And also, all the PODS Faults, including the PODS communication fault, should be qualified or disqualified during those 6 seconds. The ACU should send the Crash information for every crash event, unless for the crash event which occurs during those 6 seconds period. The ACU shall use the previous status for deployment decision during 6 seconds interval, unless there is a valid status change or PODS fault qualification, if there would be a second crash event occurred. After those 6 seconds period, the ACU should treat the PODS messages as usual, as per the required normal operation.
Fault statusPassenger Telltale lamp Airbag Warning Lamp PODS-B ECU Failure ON BTS FailureON Bladder Sensor Failure ON Communication ErrorON PODS-B
TerminalAssignmentTerminalAssignment J1850 Communication Line10J1850 Communication Line 3Vehicle Speed Signal11- 4Chassis Ground12K-Line (Body) 5Signal Ground13Keyless Entry Code Saving 6J2284 CAN High Line14J2284 CAN Low Line 7K-Line (Power Train)15L-Line 8K-Line (Chassis)16Battery Positive Data Link Connecter
Shorting bar opener ACU Connecter PinAssignmentPinAssignment 1AB driver #1 plus26Telltale lamp 2AB driver #1 minus27Crash output 3 AB passenger #1 minus 28 FIS driver plus 4 AB passenger #1 plus 29 FIS driver minus 5 Buckle Pretensioner driver plus 30FIS passenger minus 6 Buckle Pretensioner driver minus 31 FIS passenger plus 7Buckle Pretensioner passenger minus32PODS CAN-H 8 Buckle Pretensioner passenger plus 33PODS CAN-L 9 Side AB front driver plus 34SIS driver plus 10 Side AB front driver minus 35 SIS driver minus
ACU Connecter PinAssignmentPinAssignment 11Side AB front passenger minus36SIS passenger minus 12Side AB front passenger plus37SIS passenger plus 13 Curtain AB driver plus 38 STPS driver plus 14 Curtain AB driver minus 39 STPS driver minus 15 Curtain AB passenger minus 40STPS passenger minus 16 Curtain AB passenger plus 41 STPS passenger plus 17AB driver #2 plus42Buckle switch driver plus 18 AB driver #2 minus 43Buckle switch driver minus 19 AB passenger #2 minus 44Buckle switch passenger minus 20 AB passenger #2 plus 45 Buckle switch passenger plus 21 Retractor Pretensioner driver plus 46 Retractor pretensioner passenger plus 22 Retractor Pretensioner driver minus 47 Retractor pretensioner passenger minus 23 IGN 48 K-line 24 Shorting bar opener 49 GND 2550 Warning lamp
1. What type of ACU is equipped on JM?. 4B-US. HAE-3. SREHMC. AB8-E 2. What is not employed on JM's SRS?. Electrical Accelerometer. Mechanical Safing Sensor. Passenger Telltale Indicator. Buckle Pretensioner 3. Which one is correct? Choose one.. If a loss of battery supply to the ACU: the warning lamp shall be turned off continuously.. If a loss of internal operating voltage : the warning lamp shall be turned off continuously.. If a loss of microprocessor operation : the warning lamp shall be turned on continuously.. If the ACU is not connected : the warning lamp shall be turned off.
Quiz 4. If the DAB is deployed after crash, then the ACU can be reused after resetting ( ). wrong. true 5. The recorded diagnostic trouble code can be erased with disconnecting the negative battery terminal for longer than 16 seconds ( ). wrong. true
When Danger Comes From the Dashboard Air bags can be hazardous for children riding in the front seats of cars. It's safer to put kids in the back and strap them in which a seat belt. Some of the risks; (see next page)
Child under 12 Children who are less than 59 inches (150Cm) tall may be hit in the head by airbag inflating at 200 miles an hour (322 km/h).
Infant in a safety seat Very small children in a rear-facing safety seat in the front may be slammed face-first into the backrest.
Pregnant woman Some safety advocates believe the airbag's impact may harm fetuses, but evidence is inconclusive. Airbags may protect expectant mothers.