Technician Handbook 874 Engine Control Systems II Technical Training Technician Handbook 874 Engine Control Systems II Diagnostic Tools and Resources There are many troubleshooting “tools” that can be used to accurately identify and troubleshoot driveability problems These include: •  Previous troubleshooting experience •  Use of the OBD self-diagnostic system •  Service Literature – Technical Information System (TIS), Repair Manuals, Electrical Wiring Diagrams, and Technical Service Bulletins •  Techstream There are also other resources at your disposal for those extraordinary situations where your best attempts fail to resolve the customer concerns: •  Technical Assistance hotline •  Area office assistance; STSs, FTSs, and FPEs With these resources available to you, even the most difficult customer concerns can be resolved while maintaining high standards for customer satisfaction Previous Troubleshooting Experience Technical Training Your experience is one of the best resources you have Depending on the symptom or customer description of the driveability concern, you can often eliminate many sub-systems from your diagnostic investigations It is important to note, however, this does not mean that troubleshooting is performed in a random manner In fact, you will always fix the car faster and with more accuracy when you follow a systematic diagnostic approach Technician Handbook 874 Engine Control Systems II Use of the On-Board Diagnostic System All ECMs are equipped with an on-board self-diagnostic system (OBD) This system is capable of detecting shorts and opens in most sensor electrical circuits and in some actuator circuits Later models equipped with the OBD II system can also detect component and system performance These OBD systems are an integral part of your troubleshooting process and will weigh heavily in your diagnostic outcome Diagnostic Toolset The diagnostic toolset consists of the TIS Techstream, also known as the Techstream or the “Scan Tool.” Depending on the vehicle you are working on and the nature of the customer concern, this tool is extremely valuable for gathering large quantities of diagnostic data in a relatively short period of time For troubleshooting engine control system concerns, the Techstream allows you to quickly perform the following functions: •  Read and define Diagnostic Trouble Codes (DTCs) •  Display serial data stream containing sensor, actuator, and diagnostic information •  Store and playback snapshot data •  Display OBD II monitor status and results •  Test sensors and actuators dynamically using Active Tests General OBD II Scan Tool or Techstream Procedure If the Techstream cannot communicate with ECU controlled systems when connected to DLC3, the ignition switch is ON, and the Techstream is on, there is a problem on the vehicle side or tool side 1.  If communication is normal when the Techstream is connected to another vehicle, inspect the diagnosis data link line (Bus-line) or ECM (ECU) power circuit of the vehicle 2.  If communication is still not possible when the Techstream is connected to another vehicle, the problem is probably in the Techstream itself Check the Techstream Operator’s Manual or call Techstream support for help Technical Training Technician Handbook 874 Engine Control Systems II NOTE How to Proceed with Troubleshooting Operation Flow NOTE Technical Training Perform troubleshooting in accordance with the flowchart The flowchart is an outline of basic troubleshooting procedures Confirm the troubleshooting procedures for the circuit you are working on before beginning troubleshooting Refer to the Introduction section of the Repair Manual (RM) for more information 1.  Vehicle Brought to Workshop 2.  Customer Problem Analysis a.  Ask the customer about the conditions and environment when the problem occurred 3.  Inspect Battery Voltage a.  Standard voltage is between 11 and 14V Refer to the Repair Manual (RM) for vehicle specifications b.  If the battery voltage is below 11V, recharge or replace the battery before proceeding 4.  Health Check 5.  Symptom Confirmation and DTC (and Freeze Frame Data) Check a.  Visually check the wire harnesses, connectors and fuses for open and short circuits b.  Warm up the engine to the normal operating temperature c.  Confirm the problem symptoms and conditions, and check for DTCs If DTC output, proceed to step If NO DTC output, proceed to step See the Repair Manual (RM) for symptom simulation methods and more information Technician Handbook 874 Engine Control Systems II How to Proceed with Troubleshooting Operation Flow (cont’d) 6.  DTC Chart a.  Check the results obtained in step Then find the output DTC in the DTC chart within the Repair Manual (RM) Look at the “Trouble Area” column for a list of potentially malfunctioning circuits and/or parts 7.  Problem Symptoms Chart a.  Check the results obtained in step Then find the problem symptoms in the problem symptoms table within the Repair Manual (RM) Look at the “Suspected Area” column for a list of potentially malfunctioning circuits and/ or parts 8.  Circuit Inspection or Part Inspection a.  Identify the malfunctioning circuit or part 9.  Adjust, Repair, or Replace Adjust, repair or replace the malfunctioning circuit or parts 10.  Confirmation Test a.  After the adjustment, repairs or replacement, confirm that the malfunction no longer exists If the malfunction does not reoccur, perform a confirmation test under the same conditions and in the same environment as when the malfunction occurred the first time Technical Training Technician Handbook 874 Engine Control Systems II DTC Check Operation Flow In the DTC check, it is very important to determine whether the problem indicated by the DTC either: 1) still occurs, or 2) occurred in the past but has returned to normal In addition, the DTC should be compared to the problem symptom to see if they are related For this reason, DTCs should be checked before and after confirmation of symptoms (i.e., whether or not problem symptoms exist) to determine current system conditions, as shown in the flowchart Never skip the DTC check Failing to check DTCs may, depending on the case, result in unnecessary troubleshooting for systems operating normally or lead to repairs not related to the problem Follow the procedures listed in the flowchart in the correct order The flowchart shows how to proceed with troubleshooting using the DTC check Directions from the flowchart will indicate how to proceed either to DTC troubleshooting or to the troubleshooting of each problem symptom NOTE Technical Training Refer to the Introduction section of the Repair Manual (RM) for more information Technician Handbook 874 Engine Control Systems II DTC Information If the DTCs are output after the DTC check procedure is completed, use the Repair Manual (RM) for the DTC diagnostic procedure There is a lot of important information in the DTC troubleshooting sections of the Repair Manual (RM), such as the system description, monitor description, monitor strategy, typical enabling conditions, typical malfunction thresholds, wiring diagram, and inspection procedure Carefully studying this information before beginning diagnosis may help you to better understand the issue and its cause •  The Description portion provides an overview of the system operation •  The Monitor Description portion provides an overview of the monitor operation •  The Monitor Strategy portion provides information on related DTCs, required sensors/components to operate (main and related), frequency of operation (continuous or once per driving cycle), duration of operation, MIL operation, and sequence of operation •  The Typical Enabling Conditions portion provides information on specific conditions necessary for the monitor to operate, such as DTCs that cannot be present, system statuses, battery voltage, and other important conditions •  The Typical Malfunction Thresholds portion provides information on what will cause the monitor to fail and a DTC to set •  The Wiring Diagram portion provides a thorough wiring diagram of the system and components •  The Inspection Procedure portion provides the procedure for diagnosing the cause of the DTC Technical Training Technician Handbook 874 Engine Control Systems II Technical Training ... Techstream support for help Technical Training Technician Handbook 874 Engine Control Systems II NOTE How to Proceed with Troubleshooting Operation Flow NOTE Technical Training Perform troubleshooting... provides the procedure for diagnosing the cause of the DTC Technical Training Technician Handbook 874 Engine Control Systems II Technical Training ... problem symptom NOTE Technical Training Refer to the Introduction section of the Repair Manual (RM) for more information Technician Handbook 874 Engine Control Systems II DTC Information If the