COMPUTERS AND INPUT SENSORSMICROCOMPUTER OPERATION HAPPENS IN STAGESINPUT STAGEINPUT CONDITIONINGBINARY CODEPROCESSING OPERATIONTYPES OF MEMORYREAD ONLY MEMORYRANDOM ACCESS MEMORYKEEP ALIVE MEMORYPROCESSOR LOCATIONHANDLING THE PROCESSOROUTPUT STAGEOUTPUT DRIVERSINPUT SENSORS3 WIRE SENSORS REFERENCE VOLTAGE SENSOR OR VOLTAGE MODIFIERTHROTTLE POSITION SENSORTWO WIRE SENSOR VOLTAGE MODIFIERMAF SENSORCYCLE DUTY CYCLE PULSE WIDTH FREQUENCYPULSE WIDTHVANE AIR FLOW METERWHEATSTONE BRIDGEVOLTAGE GENERATORO2 SENSOR SIGNAL02 CROSSCOUNTSZIRCONIA SENSORTITANIA SENSORDIAGNOSTIC LOGIC TREELOOK UP TABLE USED TO DETERMINE BLOCK LEARN/INTERGRATORSCANNERGM PROMCODE CHARTDATA LINK CONNECTOR’S (DLC)THE THREE AMIGO’SCOMPUTERSCOMPUTERSAND AND INPUT SENSORSINPUT SENSORSCHAPTER 9ENGINE PERFORMANCEcbcMICROCOMPUTER OPERATION HAPPENS IN STAGESMemorycbcINPUT STAGEINPUTS: All sensors produce are a voltage signal of some type Some Inputs are “conditioned” before going to the microprocessor.–Amplification–A/D ConversioncbcINPUT CONDITIONINGMicroprocessor can only process some types of signalsMust amplify some signalsMust convert analog signals to digital signalscbcBINARY CODEA/D converter takes snapshot of analog signal Computers only understand 1’s and 0’s.–1 = On–0 = OffVoltages are classified into different rangesEach range is assigned a numeric valueValues are translated into a binary codecbcPROCESSING OPERATIONDigital signal compared to lookup tablesInformation is sent to microprocessorMicroprocessor decides what to doIssues a command to output actuatorcbcTYPES OF MEMORY3 DIFFERENT TYPESREAD ONLY MEMORY (ROM) RANDOM ACCESS MEMORY (RAM)KEEP ALIVE MEMORY (KAM)cbcREAD ONLY MEMORYPermanent memoryMicroprocessor can only read information from ROMInformation cannot be erasedContains info such as: programs, look up tables to tell how vehicle should perform. Data and formula’s used to perform calculationsVehicle information: # of cylinders, valve size, transmission type, rear endcbcRANDOM ACCESS MEMORYInformation stored temporarilyCan be written to or read fromWhen Ignition is turned off, memory is erased.Used to store information from sensors, results of calculations and data subject to constant change.cbcKEEP ALIVE MEMORYInformation can be read, written and erased from KAMKAM is not lost when ignition key is turned offDisconnecting Battery will erase KAMKAM allows for adaptive strategiesStores diagnostic codescbcPROCESSOR LOCATIONUsually under dash or inside carSometimes under hood. Susceptible to water, dirt, dust, heat and vibrationSome are built in to componentBody Computers located many different places in vehicle.Some cars centrally locate all processorscbcHANDLING THE PROCESSORTOUCH THE VEHICLE CHASSIS TO DISCHARGE STATIC ELECTRICITYTURN POWER OFF BEFORE DISCONNECTING PROCESSORBE SURE DVOM CONNECTIONS ARE CORRECTBE SURE TO USE THE CORRECT TEST INSTRUMENTcbcOUTPUT STAGEMicroprocessor issues commands in the form of voltagesCan display information on a Scanner or Digital dashCan control hydraulic, vacuum or electrical components.cbcOUTPUT DRIVERSMicroprocessor send digital signals to output driversDrivers usually do not send voltage to actuatorsMicroprocessor controls actuator ground circuitcbcINPUT SENSORSALL SENSORS PERFORM SAME BASIC FUNCTION–DETECT MECHANICAL CONDITION (MOVEMENT)–CHEMICAL STATE CHANGE–TEMPERATURE CONDITIONALL SENSORS CHANGE ABOVE INPUT INTO VOLTAGE SIGNALS THAT PROCESSOR CAN USEcbc3 WIRE SENSORSREFERENCE VOLTAGE SENSOR OR VOLTAGE MODIFIERVOLTAGE REFERENCESIGNAL WIRESIGNAL RETURN (GROUND)cbcTHROTTLE POSITION SENSORCHANGES MECHANICAL ACTION INTO ELECTRICAL SIGNALSOME ARE ADJUSTABLESOME READ HIGH VOLTS AT IDLE, SOME LOW VOLTS AT IDLEcbcTWO WIRE SENSORVOLTAGE MODIFIERSIGNAL CIRCUITGROUND CIRCUITTWO TYPES OF TERMISTORS–NTC = REDUCES OHMS WHEN TEMP INCREASES–PTC = INCREASES OHMS WHEN TEMP INCREASEScbcMAF SENSORUSES HOT WIRE PCM MONITORS COLD WIRE TEMP.SENDS CURRENT TO HOT WIRE TO MAINTAIN 392 DEGREES ABOVE COLD WIREAMOUNT OF CURRENT DETERMINES INTAKE AIR FLOW306CcbcCYCLEDUTY CYCLEPULSE WIDTHFREQUENCYcbcPULSE WIDTHLENGTH OF TIME IN MS, ACTUATOR IS ONIE, “DURATION OF ON-TIME”PULSE WIDTH MODULATIONcbcVANE AIR FLOW METERUSES THREE TYPES OF VOLTAGE MODIFIERS–SWITCH–POTENTIOMETER–THERMISTORMOVES DOOR TO DETERMINE AIR FLOW305CcbcWHEATSTONE BRIDGETHREE FIXED AND ONE VARIABLE RESISTORPCM ALWAYS TO BALANCE THE BRIDGEUSED TO MEASURE PRESSURE AND MECHANICAL STRAIN285CcbcVOLTAGE GENERATORGENERATES IT OWN VOLTAGE SIGNALCOMPARES INSIDE AIR TO OUTSIDE AIRSIGNAL IS .1 TO 1.0 VOLTLOW VOLTAGE MEANS SENSING LEANHIGH VOLTAGE MEANS SENSING RICHcbcO2 SENSOR SIGNALSignal range is between 0.0 and 1.0voltNormal operation is from 0.2 to 0.8 voltsPCM will always try to do the opposite from what 02 sensor is signaling417Lcbc02 CROSSCOUNTSGenerally, about 2 to 3 crosscounts is normal operationcbcZIRCONIA SENSORcbcTITANIA SENSORcbcDIAGNOSTIC LOGIC TREELOGIC TREE OR DIAGNOSTIC CHARTSOME CHARTS INCLUDE EXPLANATIONSMANY MANUFACTUERS USE THIS TYPE DIAGNOSTICScbcLOOK UP TABLE USED TO DETERMINE BLOCK LEARN/INTERGRATORcbcSCANNERSCANNERS READ CODES AND DATA STREAMSTEST ACTUATORSGRAPHING LAB SCOPEDVOMTECHNICAL INFOcbcGM PROMCONTAINS SPECIFIC PROGRAMS SUCH AS; SPARK ADVANCE, FUEL INJECTIONSOME ARE ELECTRONICALLY ERASABLEREPLACEABLE SEPARATE FROM PCMLAB PG 379cbcCODE CHARTSELF DIAGNOSTICS (SELF TEST MODE)“HARD FAULTS”“SOFT CODES” OR “MEMORY CODES”ACCESS TROUBLE CODES WITH SCANNER OR BY MANUAL METHODERASING FAULT CODEScbcDATA LINK CONNECTOR’S(DLC)LAB PAGE 391cbcTHE THREE