ATASA 5 th. Detailed Diagnosis & Sensors. Please Read The Summary

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1 ATASA 5 TH Study Guide Chapter 26 Pages Points Please Read The Summary

2 1. Many different sensors are involved in the overall driveability of a vehicle. Input Processing Output

3 Electronic Engine Control System Block Diagram

4 ABS Chassis SRS HVAC Anti Theft Body Scan Tool Sensors Inputs PCM DLC HO2S MIL TPS ECT Engine Outputs Actuators Ignition Spark IAT MAF MAP CKP CMP Open Loop Mode Closed Loop Mode Clear Flood Mode Limp In Mode EFI Emission Controls Cruise Accessories P/N KS VSS Electronic Engine Control System Block Diagram

5 Sensors Upstream (A/F) & Downstream (CAT) HO2S TPS ECT IAT MAF MAP CKP CMP P/N ABS Chassis Inputs SRS HVAC Anti Theft PCM PROM & RAM Engine Open Loop Mode Closed Loop Mode Clear Flood Mode Limp In Mode Outputs Body DLC MIL Actuators Ignition Spark EFI (injectors & IAC) Emission Controls (6) CAT AIR PCV TAC EVAP EGR Cruise Scan Tool DTC s Accessories Instrument Cluster KS VSS Electronic Engine Control System Block Diagram

6 2. In an OBD II system, monitors set a and the ECM or PCM illuminates the. DLC, MIL DTC, MIL DTC, M&M

7 3. Diagnosis should begin with a thorough inspection to eliminate simple things. Under Body Under Roof Under Hood

8 4. Even though a DTC is retrieved, there is more than possible cause for most problems. One Ten Fifty

9 Conditions to set DTC s Some diagnostic tests (monitors) run continuously Some diagnostic tests (monitors) run Once per trip Enable criteria met Diagnostic test is run IF results of the test are outside PCM parameters Type A DTCs turn on light after 1 failure Type B DTCs require 2 consecutive trips w/failure

10 Only A & B codes will illuminate the MIL

11 DTCs in 5 Character Format 1 st character letter (Body PPWR/TRN Chassis Uart) 2 nd character 0generic 1Manufacturer Specific 2Manufacturer Specific 3 rd Character Fuel & Air Metering 2 Inj. Circuits 3 Ignition or Misfire 4 Emissions Controls 5 Vehicle Speed control and idle controls 6 Computer Output Circuit 7 & 8 Transmission

12 The last 2 digits indicate the component or system section that has the fault Remember: More Testing Needed! Meter, Scope, Gauges, TSB Check, etc. 1 = Fuel and Air Metering 2 = Fuel and Air Metering (Injector circuits only) 3 = Ignition System or Misfire 4 = Auxiliary Emission Controls 5 = Vehicle Speed Control and Idle Control System 6 = Computer Output Circuit 7 = Transmission 8 = Transmission

13 5. If OBD II monitors (self tests) have not been run, a may be present but a DTC not set. Monitor Systems Once per Trip Flags Catalytic Converter O2 Sensor O2 Heater EGR AIR EVAP Continuously Monitored No Flags Comprehensive Component Monitor Misfire (counter & cylinder ID) Fuel Trim (STFT & LTFT) Fault Issue Code

14 6. data associated with a DTC should be retrieved and studied. Freeze Frame Frozen Frame Movie Shot

15 7. freeze frame (MFF) is not part of regular DTC freeze frame data. MISFIRE MONITORING CONTINUOUS Mineral Misfire Misdiagnosis

16 8. Mode data shows out of range values that did not trigger a DTC very useful in diagnostics! $01 $02 $06

17 9. Driveability problems without DTCs require a tech to do based diagnostics. Strategy Symptom Complaint

18 10. Basic DMM and checks can verify sensor as well as actuator activity. Fuel Pressure Fault Code Lab Scope

19 11. All sensors perform the same basic functions of detecting conditions, states or conditions & change that into electrical signals the PCM understands. Mechanical, Thermal, Hydraulic Mechanical, Chemical, Pneumatic Mechanical, Chemical

20 12. On a lab scope, the vertical axis is the scale, the horizontal axis is base or sweep, and the trigger is the signal that tells the scope to start drawing the pattern on the screen. Voltage, Ohms Voltage, Time Voltage, Frequency

21 13. A waveform can be referred to in order to find out what a normal trace looks like. Library Dictionary Thesaurus

22 14. Good and clean are key to properly functioning circuits. Connections, Grounds Connections, Voltages Connections, Sources

23 15. A test is a quick way of testing the condition/integrity of any wire. Ohms Law Voltage Available Voltage Drop

24 16. EMI is electromagnetic in a signal due to a poor ground or a positive side issue. Noise Interference Static

25 17. Voltage spikes in solenoid circuits are captured by diodes. Clamping Stamping Zener

26 18. The job of is to do on off digital signaling. Sensors Actuators Switches

27 19. sensors are NTC thermistors, (ECT, IAT, CHT, TFT) & can be DMM checked. Pressure Temperature Position

28 20. sensors are piezo resistive and can be best checked with a lab scope. Pressure Temperature Position

29 21. A pressure sensor is similar in operation to a MAP, it measures EVAP system pressure. Vapor Fuel Water

30 22. feedback pressure sensors (DPFE) and fuel rail pressure sensors are also piezo resistive. CAT EGR PCV

31 23. The (MAF) measures the flow of air entering the engine. The MAF is typically a hot wire wheatsone bridge. A very touchy sensor a piece of dust can make it act up. Mass Air Flow Mass Air Management Mass Air Temperature

32 24. If you lightly on a MAF with the handle of a screwdriver and it starts to act up, replace it. Slam Hammer Tap

33 25. Typical MAF readings at idle are to grams per second of airflow. 1 to 2 4 to 7 10 to 12

34 26. The sensor (HO 2 S) is the key sensor in closed loop mode. Exhaust Gas Oxygen Exhaust Vapor Pressure Exhaust Gas Omission

35 27. HO 2 S are used for A/F control. Upstream Midstream Downstream

36 28. HO 2 S are used as a catalyst efficiency monitor. Upstream Midstream Downstream

37 29. Oxygen sensors can be narrow range (ZrO2) or wide range (TiO2). Zirconium, Titanium Zippo, Titania Zirconium, Tilapia

40 30. Zirconium Dioxide & Titanium Dioxide sensor produce voltage the same way. True or False

41 31. A ZrO 2 HO 2 S can fail be being biased either or, may not work at all, or may be slow. Rich, Lean Rich, Loose Pitch, Lean

42 32. The upstream HO 2 S should have cross counts over & under the.450 volts every 5 seconds

43 33. The position sensor is a 5 volt reference potentiometer. Throttle Manifold Tumble

44 34. Electronic throttle control will have 2 and 2 accelerator position sensors. MAF MAP TPS

45 35. Watch a TPS with a for an even sweep without dropoffs (breaks) or spikes. Multi meter Lab Scope Noid Light

46 36. speed sensors are magnetic generators. (aka: variable reluctance sensors) Vehicle, Pulse Transmission, Pulse Crankshaft, Telsa

47 37. effect sensors can be used a crankshaft position (CKP) & camshaft position sensors(cmp). Stall Hall Crawl

48 38. Using a trace lab scope, CKP and CMP can be checked for their synchronization. Dual Triple Quad

49 39. A sensor (KS) is a piezo generator that generates a voltage when vibration is applied. Kinikinic Knock Knack

50 40. Generally speaking, are electromechanical devices that convert an electrical current into a mechanical action. Actuators are typically solenoids, motors, or lights. Outputs controlled by the PCM include devices such as: Solenoids Relays Motors Lights Diagnostics (DTCs) These components control the operation of systems such as: A/C Compressor Clutch / AIR / Cooling Fan /Cruise Control / Diagnostics (DTCs) / MIL / Engine Torque Mgmt / EVAP / Fuel Pump / EGR / Fuel Injector(s) / Idle Air Control (IAC) / Ignition Control (IC) / Intake Manifold Tuning / Shift Light / Throttle Control / Transmission Converter Clutch (TCC) / Transmission Pressure Control / and Transmission Shift Actuators Sensors Inputs

51 41. Actuators can be tested with lab scopes for their width, signal, and voltage waveforms (signatures). Performance, Frequency Sweep, Amplitude Pulse, Frequency

52 42. Following repairs, a system should be checked to operation. A test drive should be done to take the vehicle through a drive cycle that will complete the OBD II diagnostic monitors. Quantify Verify Mummify

Auto Diagnosis Test #7 Review

Auto Diagnosis Test #7 Review Your own hand written notes may be used for the 1 st 10 minutes of the test Based on Chapters 25, 26, 32, 33, 34 and Lab Demonstrations Auto Diagnosis Test #7 Review Your