CONTENTS 1. Basic Theory 2. NF AIR BAG SYSTEM 3. PARTS OF ADVANCED AIR BAG SYSTEM 4. Electrical Interface Requirements 5. System Diagnostics and Fault Handling
OBJECTIVE Understanding of TRWs GEN 5.6 ACU Understanding of RAS II (TRWs Impact Sensor) Understanding of new component – PAD Switch Understanding of NFs Advanced Air Bag System components
PRECAUTIONS Be sure to proceed after approx. 30 seconds or longer from the time the ignition switch is turned to the LOCK position and the negative (-) battery cable is disconnected from the battery. Never use airbag parts from another vehicle. When replacing parts, replace them with new parts. Never attempt to disassemble and repair the air bag modules (DAB, PAB, SAB, BPT), clock spring and wiring in order to reuse them. Dont check the resistances of DAB, PAB, CAB, SAB module without SST.
Purpose of enactment for USA Advanced Air-bag regulation * To protect infants, children and female drivers from be damaged by air bag * To enhance the protection performance in variation of the different size of the passenger or in condition that the seat belt is fastened or not Number of victims by air bag (1986 ~ /1) Main type of victims by air bag * Infants seated in the infant s seat installed at the rear seat * Child who does not fasten the seat belt or fasten inappropriate seat belt * Adult who sits near air bag (especially, female driver or assistance passenger at inappropriate position)
APPLICATION of NF Air Bag OptionDOMGENEUR/AUSUSA/CANREMARK Driver DepoweredSOS- Advanced---S Passenger DepoweredOOS- Advanced---S Curtain airbagOOSS All Of CAB OOSS Employed with curtain air bag O : Option S : Standard
EF VS NF Comparative table (EUR, GEN) EFNFRemark ACUSIEMENSTRW GEN 5.6 PPDOXDAB, PAB, PT(Belt & Buckle) would be deployed when ACU detect frontal crash Buckle Switch signalOX PAD S/WXO Rear Side AirbagXX
MAJOR COMPONENT ACU: Airbag Control Unit FIS: Front Impact Sensor (2pcs.) SIS: Side Impact Sensor (2pcs.) DAB: Driver Airbag – 1 stages squib (Advanced airbag: 2 squibs) PAB: Passenger Airbag - 1 stages squib (Advanced airbag: 2 squibs) FSAB: Front Side Airbag – 1 squib CAB: Curtain Airbag – 1 squib OCS: Occupant Classification System (Advanced airbag only) SPT: Seatbelt Pre-tensioner & Buckle Pre-tensioner STPS: Seat Track Position Sensor (Advanced airbag only) BS: Buckle Sensor (Advanced airbag only) PAD S/W: Passenger Airbag Deactivation (Disable) Switch
1) DC/DC Converter The DC/DC converters of the power supply (Combined Asic) includes a step up and a step down converter, which provides the firing voltage for two firing circuits and the internal operation voltage of the ACU. If the internal operating voltage falls below a defined threshold a reset is executed. 2) System Watchdog The ACU shall have a watchdog timer that shall reset the microprocessor if it is determined to be executing code improperly. If the watchdog timer does not receive the refresh signal within 46.5 to 53.5 mSec. it shall reset the microprocessor for normal operation. When the ACU is first powered up the first refresh signal shall be sent within 43.7 to 51.8 mSec. to accommodate special start up testing. The watchdog shall be tested each key-on cycle by way of stopping the refresh for a period of time, which will guarantee a reset of the module for a working watchdog circuitry. If this reset does not occur, the Watchdog Test Failure fault shall be logged and shall remain for the remainder of the ignition cycle ACU - Descriptions for internal functions
3) Non Volatile memory Data stored in non-volatile memory shall include the following: 1) Service Information (Fault Recording) See section Diagnostic Fault Code Assignment for details 2) Event Recording (Crash record Frontal and Side) see section Data Structure of Each Crash Record. 4) X/Y-Acceleration Sensor The integrated electrical accelerometer provides an electrical representation of the vehicle's acceleration along the longitudinal and orthogonal axis. The electrical signals are proportional to the acceleration. Those signals are evaluated by the microcontroller via the 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 ACU - Descriptions for internal functions
5) Arming / Safing Circuit A trigger switch controlling a power FET is implemented as arming/safing sensor in the ACU. It is included only in the frontal airbag firing loops and has the function of arming the frontal airbag and belt-pretensioner firing circuits under all required deployment conditions and maintaining the airbag firing circuits unarmed under conditions of lower acceleration levels in the sensing direction. The function of the Safing Circuit can be tested, so a high level of reliability can be achieved. 6) Firing Loops Front and Side Airbags Each firing loop consists of a high side and low side switch. The current is limited by the ASICs to A. Both stages of the front airbags and all front seat side restraints including inflatable curtain bags are fired out of the energy reserve capacitors see section Firing and Logic Back-up Capacity Rear seat side restraints are fired directly out of the ignition supply voltage
7) Firing Loops Belt and Buckle Pretensioners Each firing loop consists of a high side and low side switch. The current is limited by the ASICs to A. The Belt and Buckle pretensioners in both driver and passenger seats are fired out of the energy reserve capacitors see section Firing and Logic Back-up Capacity 8) Energy Reserve and Autonomous Operating Time The ACU has an energy reserve that ensures the internal operation of the central unit and buffered firing circuits for a minimum of 150ms after loss of battery power. Maximum 10seconds after battery voltage removal from the ACU it shall not longer be capable of detecting a crash or deploying the airbags. Full energy reserve capability is available 10 seconds after the minimum specified operating voltage has been applied to the ACU power line. ACU - Descriptions for internal functions
EF(SIEMENS)NF(TRW GEN5.6) Front (DAB & PAB) By BPS Side (SAB & CAB)By batteryBy BPS Pre-tensioner (seat belt & buckle)By batteryBy BPS ** BPS : Back up Power Supply ACU - Descriptions for internal functions
Main crash detection sensor Safing sensorSupplemental detection sensor Frontal crashACU-XACU SAFING-XFIS-DRV & PASS DRV Side crashSIS-DRVACU-YNone PASS Side crashSIS-PASSACU-YNone Crash Sensor ACU - Descriptions for internal functions
ACU - Firing Circuit parameters Given the firing resistance ranges specified in the Performance Specification, the NF GEN 5.6 shall be able to supply to the inflator module squibs a minimum firing current of: 1.3 A averaged over the first 2ms of current flow for the frontal airbags including dual stage inflators 980 mA averaged over the first 2ms of current flow for the buckle and belt pretensioners 1.3A averaged over the first 2ms of current flow for the front side airbags and curtain airbags
GEN 5.6 Firing Loop resistance Parameters Total Resist Total Wiring harness resist Connections Squib resist Clock Spring MinMaxMinMaxQtyMinMaxMinMaxMinMax Driver AirbagNFGasoline Eng Diesel Eng NFAAdvanced 1 st stage Advanced 2 nd stage Passenger Airbag NFDepowered NFAAdvanced 1 st stage Advanced 2 nd stage Belt- Pretensioner NFDriver Passenger NFADriver
GEN 5.6 Firing Loop resistance Parameters Buckle- Pretensioner NFDriver Passenger NFADriver Passenger Front Side Airbag Driver Passenger Curtain Airbag Driver Passenger WIRE TYPE : AVSS 0.5SQ(0.0327ohm/m +/-xx ohm) 2. Maximum tolerance of wiring harness dimension : +/-10mm(excluding DAB), DAB minimum wiring harness tolerance : -90 ~ -80mm 3. The Number of connections ; to be conducted high side pin of ACU and low side pin via routine of wiring harness
DAB(Driver Air Bag) Resistance: OHMS All-fire current: 1.2A for 3ms. No-fire current: single pulse of 0.4A for 10 sec Cyclic test current: 100mA Inflator Assembly (Depowered : 1 stages squib, Advanced : 2 squibs) Mounting plate (Reaction Plate) Module cover (Trim cover) Hidden "H"-pattern tear seam Bag: coated L (Front half surface) 2-vent holes
PAB(Passenger Air Bag) Resistance: OHMS All-fire current: 1.2A for 2ms. No-fire current: single pulse of 0.4A for 10 sec Cyclic test current: 100mA Inflator Assembly(Depowered : 1 stages squib, Advanced : 2 squibs) Mounting plate Module cover (Trim cover) U-pattern tear seam Inserted in Crash pad assembly Bag: not coated with no vent hole
FSAB (Frontal Side Air Bag) Resistance: OHMS All-fire current: 1.75 A for 2ms. No-fire current: single pulse of 0.65 A for 2 sec Cyclic test current: 10 mA Single Output
CAB(Curtain Air Bag) Resistance: ohms All-fire current: 1.75A for 2ms. No-fire current: single pulse of 0.65A for 2s. Cyclic test current: 10mA Single Output CAB MARK
SPT(Seatbelt Pre Tensioner) When a vehicle has crashed with a certain degree of frontal impact, the gas generator is made to ignite by the electrical firing signal from SRSCM. Gas from the gas generator causes movement of the piston in the manifold case (cylinder), which operates a rack gear. Finally the webbing is retracted by the rotation of the spool. Therefore the seat belt pretensioner helps to reduce the severity of injury to he front occupant by retracting the seat belt webbing to prevent the occupant from moving forward and hitting the steering wheel or instrument panel when the vehicle is crashed.
RAS ApplicationLocation OptionsAxisAccel. Range Options Frontal impact crush zone sensorFrontal Impact Crush Zone± x axis± 250g Side impactCrush Zone± z axis± 250g RASII Locations and Acceleration Ranges
Belt Buckle Sensor (Hall Effect) * N/A only Nominal current values are : State Nominal Current Range Unbuckled 4 – 7 mA Buckled 12 – 18 mA The ACU shall be capable of sensing the following Seat Belt Buckle statuses for each front seat : 1. Seat Belt Buckle fastened 2. Seat Belt Buckle not fastened 3. Seat Belt Buckle instable 4. Open / Short to Battery 5. Short to Ground 6. Defect There is no buckle switch signal in EUR & GEN vehicle.
PARTS OF ADVANCED AIR BAG SYSTEM OCS (Occupant Classification Sensor) It is one kind of passenger detecting system comprised in Advanced Air bag system for requirement of the North America Regulation. Advanced Airbag system has different unfolding condition of air bag in accordance with the condition of the passengers in order to protect any damages occurred by the air bag. OC Sensor is a device transmitting the seat condition of the passenger in three phases to Air Bag ECU for satisfying the Requirement. There is no PPD or OCS (Occupant detection system) in EUR & GEN vehicle. Instead of PPD or OCS, PAD S/W is adopted.
PARTS OF ADVANCED AIR BAG SYSTEM OCS (Occupant Classification Sensor) FSR(Force Sensing Resister) OCE(Occupant Classification Electronics) CONNECTOR OC Sensor Matt ClassDecision on Seat Criterion of Passenger Weight Deployment Class 0No one seatedNo passengerX Class 1On Child SeatedLess than 30kg (under 6 age)X Class 2 More than 5% Female is seated More than 48kg (heavier than female) O Deployment of PAB according to the class (kinds of passenger)
PARTS OF ADVANCED AIR BAG SYSTEM OCS (Occupant Classification Sensor) 1. detecting seated or not 2. Decision Person or Child Seat 3. Strat classifying Person Class Pressure exist Person Received value from 56 FSR installed at OC Matt Baby safety seat Class 1Class 2 ChildAdult CRS Module DOP Module No Pressure (Class0) Structure of Algorism pattern decision
PARTS OF ADVANCED AIR BAG SYSTEM OCS (Occupant Classification Sensor) Legs of baby safety seat Central holeHole of regular shape CRS (Child Restraint System) Module
PARTS OF ADVANCED AIR BAG SYSTEM OCS (Occupant Classification Sensor) Passenger restraints activation with OCS OCS Status Response message Tell-tale Lamp Pass front bag Pass belt Pretensioner Pass buckle Pretensioner Pass front Side bag Phase-upON->OFFDefault Class 0 = EmptyONDisabled Disable Class 1 = ChildONDisabled Enable Class 2OFFEnable DefectDefault The OCS response message to ACU affects the activation of the front passenger airbag, passenger buckle pretensioner passenger belt pretensioner and passenger front side airbag. The ACU shall interpret response of OCS as follows :
STPS (Seat Track Position Sensor) Front positionRear position
STPS (Seat Track Position Sensor) * Sensor for detecting the seat position to determine the amount of the air bag unfolding in regarding with the passenger position at the ECU. * Classification of Passenger The size of the passenger is determined by the 5-Lock Pitch position of the SEAT TRACK in front direction
STPS (Seat Track Position Sensor) A zone (5% Dummy) : Unfolding with small amount B zone (50% Dummy) : Full Unfolding * Sensing type : Proximity Switch Type (Sensing is performed by the variation of the magnetic field due to the approaching to the magnetic field) * Activated Zone : 0~18mm * Deactivated Zone : more than 26mm * Critical Zone : Zone in which sensing may be performed or not (26-18=8mm)
STPS (Seat Track Position Sensor) Nominal current values are : State Nominal Current Range Forward 5-7mA Rearward 12-17mA The ACU shall be capable of sensing the following seat position statuses, for each front seat : 1. Seat Forward 2. Seat Rearward 3. Seat position instable 4. Open / Short to Battery 5. Short to Ground
Airbag (SRS) Warning Lamp Operations During start-up phase, the warning lamp shall be commanded ON for 6 seconds (+/- 10 %) and OFF for 1 second. Thereafter, the lamp shall be commanded ON only under the following cases: 1. Lamp latch condition 2. Qualified fault is present 3. During communication with service tool.
SRS Warning Lamp latch The SRS warning lamp shall be latched ON if certain conditions are present. Some lamp latch conditions can be cleared by the service tool while others require the replacement of the ACU. Below is a description of each condition: Lamp Latch condition that can be cleared by the service tool: different external faults except Vbatt too low are qualified in the ACU. 2. A certain external fault except Vbatt too low has qualified 10 times in the ACU. 3. Belt pretensioner only firing (
Passenger Airbag Disable (PAD) Indicator Operation The ACU shall be designed with circuitry and software to drive either a PAD or a tell-tale lamp. PAD lamp will be used for depowered systems, while the tell-tale lamp will be used for he advanced systems. For the PAD indicator circuitry to function properly both the ACU and PAD Indicator shall be sourced from the same ignition line. During phase-up, the PAD indicator shall be commanded ON for 4 seconds (+/- 10 %) and OFF for 3 second. Thereafter, the lamp shall be commanded ON as long as either of the following condition exists: 1. PAD switch is in the disable position. (Only in depowered systems) 2. If OCS send an empty (Class 0) or a child (Class 1) classification to the ACU. (Only in advanced systems)
Seat-Belt Reminder function (for Advanced system only) The ACU shall support command signal generation function for Passenger side Seat-Belt Reminding (SBR) system that will be controlled by vehicle Body Control Module (BCM). Note that ACU will only collect data for necessary information for SBR on (alarming) condition and generate single pulse signal in case of on condition. Actual alarming processes such as driving alarm device (lamps and buzzers etc) and time-control of alarm will be carried out by BCM.
When a deployment occurs, or when a rear crash is detected, the Crash Output is activated. The Crash Output will have the capability to sink a minimum of 15 mA to ground from Vbatt, and a 1.2 k source or from Vcc and a 470 source, under normal operating conditions. The waveform of the output will be to activate the output within 100 ms (± 10%) of the airbag or pretensioner deployment, or rear crash detection and hold the output for 200 ms, ± 10%. The purpose of this 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.
System Diagnostics and Fault Handling - Diagnostic Fault Code Assignment The ideal fault qualification and de-qualification time for a specific fault are as following; Fault Qualification time = Qualification counts X Sampling interval Fault de-qualification time = de-qualification counts X Sampling interval The sampling interval for possible fault conditions are 0.1 second excluding following fault conditions
Fault sampling interval Table Fault Descriptions Sample Time (sec) Remarks Squib Interconnection Fault0.1 FIS failures (defect, communication failure)0.001 SIS front failures (defect, communication failure)0.001 SIS rear failures (defect, communication failure)0.001 Passenger side occupant classification sensor defect0.4 Passenger side OCS failure(communication error, Wrong ID) 0.4 WCS failure(sensor defect, communication error, Wrong ID) 0.4 Fault sampling interval Table
Fault sampling interval Table Passenger airbag tell tale Lamp failure0.025 Passenger airbag disable lamp failure0.025 SRS Warning lamp Failure0.025 Internal fault- Replace the ACU0.1 Crash recorded in 1st Stage onlyN/A Fault is qualified right after the failure condition is detected Crash recorded in Full stageN/A Crash recorded Side Airbag front-DriverN/A Crash recorded Side Airbag front-PassengerN/A Crash recorded - Belt pretensioner onlyN/A Crash recorded – Pass side with PAB inhibited (no deployment) N/A Maximum Belt Pretensioner Crash Detection ReachedN/A Rear impact detectedN/A
GEN 5.6 Firing Loop resistance Parameters Total Resist Total Wiring harness resist ConnectionsSquib resistClock Spring MinMaxMinMaxQtyMinMaxMinMaxMinMax Driver AirbagNFGasoline Eng Diesel Eng NFAAdvanced 1 st stage Advanced 2 nd stage Passenger Airbag NFDepowered NFAAdvanced 1 st stage Advanced 2 nd stage Belt- Pretensioner NFDriver Passenger NFADriver Passenger
GEN 5.6 Firing Loop resistance Parameters Buckle- Pretensioner NFDriver Passenger NFADriver Passenger Front Side Airbag Driver Passenger Curtain AirbagDriver Passenger WIRE TYPE : AVSS 0.5SQ(0.0327ohm/m +/-xx ohm) 2. Maximum tolerance of wiring harness dimension : +/-10mm(excluding DAB), DAB minimum wiring harness tolerance : -90 ~ -80mm 3. The Number of connections ; to be conducted high side pin of ACU and low side pin via routine of wiring harness
Fault Recovery and Erase 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. The ACU shall not de-qualify the following faults: NoFault CodeFault description 1B1620Internal fault 2B1650Crash recorded in Stage only (Frontal - Replace ACU) 3B1670Crash recorded in Full stage (Frontal - Replace ACU) 4B1651Crash recorded (Driver Side – Replace ACU) 5B1652Crash recorded (Passenger Side – Replace ACU) 6B1655Crash recorded – Pass side with PAB inhibited (no deployment) 7B1658Maximum Belt Pretensioner Crash Detection Reached
Fault Recovery and Erase 8B1657Crash recorded – Belt pretensioner only (
Fault Recovery and Erase System faults (stored memory contents of active and historic trouble codes) can be erased by a serial diagnostic tester. All of the faults shall be erasable when the active fault conditions are eliminated, except for the following specific faults: NoFault CodeFault description 1B1620 Internal fault 2B1650 Crash recorded in Stage only (Frontal - Replace ACU) 3B1670 Crash recorded in Full stage (Frontal - Replace ACU) 4B1651 Crash recorded (Driver Side – Replace ACU) 5B1652 Crash recorded (Passenger Side – Replace ACU) 6B1655 Crash recorded – Pass side with PAB inhibited (no deployment) 7B1658 Maximum Belt Pretensioner Crash Detection Reached DTC s not erasable by Service tool