start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 63, the reader should be able to: • • • • List the steps of the diagnostic process Describe the simple preliminary tests that should be performed at the start of the diagnostic process List six items to check as part of a thorough visual inspection Explain the troubleshooting procedures to follow if a diagnostic trouble code has been set Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 63, the reader should be able to: • • • Explain the troubleshooting procedures to follow if no diagnostic trouble code has been set Discuss the type of scan tools that are used to assess vehicle components Describe the methods that can be used to reprogram (reflash) a vehicle computer Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: data link connector (DLC) • drive cycle flash code retrieval key–on–engine off test (KOEO) • key–on–engine running test (KOER) pending code • paper test self-test automatic readout (STAR) • smoke machine technical service bulletin (TSB) • trip Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 THE EIGHT-STEP DIAGNOSTIC PROCEDURE It is important that all automotive service techs know how to diagnose and troubleshoot engine computer systems The diagnostic process eliminates known-good components or systems in order to find the root cause of automotive engine performance problems All manufacturers recommend a diagnostic procedure, and the plan suggested in this chapter combines most of the features of these plans plus steps developed in real-world problem solving Many different things can cause an engine performance problem or concern The service technician has to narrow the possibilities to find the cause of the problem and correct it Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 A funnel is a way of visualizing a diagnostic procedure At the wide top are the symptoms of the problem; the funnel narrows as possible causes are eliminated until the root cause is found and corrected at the bottom Figure 63–1 A funnel is one way to visualize the diagnostic process The purpose is to narrow the possible causes of a concern until the root cause is determined and corrected The wide range of possible solutions must be narrowed to the most likely and these must eventually be further narrowed to the actual cause Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman Continued ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 63–2 Step #1 is to verify the customer concern or problem If the problem cannot be verified, then the repair cannot be verified Step #1 Verify the Problem (Concern) Be certain a problem exists If the problem cannot be verified, it cannot be solved or tested to verify that the repair was complete Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The driver of the vehicle knows much about the vehicle and how it is driven Before diagnosis, always ask the following questions: Is the malfunction indicator light (check engine) on? What was the temperature outside? Was the engine warm or cold? Was the problem during starting, acceleration, cruise, or some other condition? How far had the vehicle been driven? Were any dash warning lights on? If so, which one(s)? Has there been any service or repair work performed on the vehicle lately? Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: Many engine performance faults are often the result of something being knocked loose or a hose falling off during repair work Knowing that the vehicle was just serviced before the problem began may be an indicator as to where to look for the solution to a problem NOTE: Because drivers differ, it is sometimes the best policy to take the customer on the test drive to verify the concern After the nature and scope of the problem are determined, the complaint should be verified before further diagnostic tests are performed A sample form that customers could fill out with details of the problem is shown in Figure 63–3 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 63–3 A form that the customer should fill out if there is a driveablilty concern to help the service technician more quickly find the root cause See the complete form on Page 764 of your textbook Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman Continued ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 63–21 The J2534 pass-through reprogramming system does not need a scan tool to reflash the PCM on most 2004 and newer vehicles A J2534 pass-through system is a standardized programming and diagnostic system It uses a personal computer (PC), a standard interface to a software device driver, and a hardware vehicle communication interface The interface connects to a PC, and to a programmable ECM on a vehicle through the J1962 data link connector (DLC) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The software for a typical pass-through application consists of two major components including: The part delivered by the company that furnishes the hardware for J2534 enables the pass-through vehicle communication interface to communicate with the PC and provides for all Vehicle Communication Protocols as required by SAE J2534 It also provides for the software interface to work with the software applications as provided for by the vehicle manufacturers Figure 63–22 A typical J2534 universal reprogrammer that uses the J2534 standards Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The second part of the pass-through enabling software is provided for by the vehicle manufacturers This is normally a subset of the software used with their original equipment manufacturer (OEM) tools and their website will indicate how to obtain this software and under what conditions it can be used Refer to the National Automotive Service Task Force (NASTF) website for the addresses for all vehicle manufacturers’ service information and cost Visit the National Automotive Service Task Force on the Internet at www.nastf.org Since the majority of vehicle manufacturers make this software available in downloadable form, having an Internet browser (Explorer/Netscape/Firefox) and connection is a must Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 MANUFACTURER’S DIAGNOSTIC ROUTINES Each vehicle manufacturer has established their own diagnostic routines and they should be followed Most include: Step #1 Retrieve diagnostic trouble codes Step #2 Check for all technical service bulletins that could be related to the stored DTC Step #3 If there are multiple DTCs, the diagnostic routine may include checking different components or systems instead of when only one DTC was stored Step #4 Perform system checks Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Step #5 Perform a road test matching the parameters recorded in the freeze-frame to check that the repair has corrected the malfunction Step #6 Repeat the road test to cause the MIL to be extinguished NOTE: Don’t clear codes (DTCs) unless instructed by service info Following the vehicle manufacturer’s specific diagnostic routines will ensure that the root cause is found and the repair verified This is important for customer satisfaction Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 COMPLETING SYSTEM REPAIRS After the repair has been successfully completed, the vehicle should be driven under similar conditions that caused the original concern Verify that the problem has been corrected To perform this test drive, it is helpful to have a copy of the freeze-frame parameters that were present when the DTC was set By driving under similar conditions, the PCM may perform a test of the system and automatically extinguish the MIL This is the method preferred by most vehicle manufacturers The DTC can be cleared using a scan tool, but then that means that monitors will have to be run and the vehicle may fail an emission inspection if driven directly to the testing station Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PROCEDURE FOR RESETTING THE PCM The PCM can be reset or cleared of previously set DTCs and freezeframe data in the following ways: Driving the vehicle Drive the vehicle under similar conditions present when the fault occurred If the PCM performed the noncontinuous monitor test and passed three times, the PCM will extinguish the MIL This is the method preferred by most manufacturers, however, this method could be time consuming If three passes cannot be achieved, the owner of the vehicle will have to be told that even though the check engine light (MIL) is on, the problem has been corrected and the MIL should go out in a few days of normal driving Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Clear DTCs Using a Scan Tool A scan tool can be used to clear the diagnostic trouble code (DTC), which will also delete all of the freeze-frame data The advantage of using a scan tool is that the check engine (MIL) will be out and the customer will be happy that the problem (MIL on) has been corrected Do not use a scan tool to clear a DTC if the vehicle is going to be checked soon at a test station for state-mandated emission tests Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Battery Disconnect Disconnecting the negative battery cable will clear DTCs and freeze-frame, erase radio station presets and other memory items on many vehicles Most vehicle manufacturers not recommend that the battery be disconnected to clear DTCs and it may not work on some vehicles The Brake Pedal Trick If the vehicle manufacturer recommends the battery be disconnected, first disconnect the negative battery cable and then depress the brake pedal Because the brake lights are connected to battery power, depressing the brake pedal causes all of the capacitors in the electrical system and computer(s) to discharge through the brake lights Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 ROAD TEST (DRIVE TRACE) Use the freeze-frame data and test-drive the vehicle so the vehicle is driven to match the conditions displayed on the freeze-frame If the battery has been disconnected, then the vehicle may have to be driven under conditions that allow the PCM to conduct monitor tests This drive pattern is called a drive cycle The drive cycle is different for each vehicle manufacturer but a universal drive cycle may work in many cases In many cases performing a universal drive cycle will reset most monitors in most vehicles Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Universal Drive Cycle Preconditioning: Phase MIL must be off No DTCs Fuel fill between 15% and 85% Cold start—Preferred = 8-hour soak at 68°F to 86°F Alternative = ECT below 86°F With the ignition off, connect scan tool Start engine and drive between 20 and 30 mph for 22 minutes, allowing speed to vary Stop and idle for 40 seconds, gradually accelerate to 55 mph Maintain 55 mph for minutes using a steady throttle input Stop and idle for 30 seconds, then accelerate to 30 mph Maintain 30 mph for 12 minutes Repeat steps and four times Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Using scan tool, check readiness If insufficient readiness set, continue to universal drive trace phase II Important: (Do not shut off engine between phases) Phase II: Vehicle at a stop and idle for 45 seconds, then accelerate to 30 mph Maintain 30 mph for 22 minutes Repeat steps and three times Stop and idle for 45 seconds, then accelerate to 35 mph Maintain speed between 30 and 35 mph for minutes Stop and idle for 45 seconds, then accelerate to 30 mph Maintain 30 mph for 22 minutes Repeat steps and five times Using scan tool, check readiness Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY Funnel diagnostics—Visual approach to a diagnostic procedure: Step Step Step Step Step Step Step Step Verify the problem (concern) Perform a thorough visual inspection and basic tests Retrieve the diagnostic trouble codes (DTCs) Check for technical service bulletins (TSBs) Look carefully at scan tool data Narrow the problem to a system or cylinder Repair the problem and determine the root cause Verify the repair and check for any stored DTCs Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Care should be taken to not induce high voltage or current around any computer or computer-controlled circuit or sensor A thorough visual inspection is important during the diagnosis and troubleshooting of any engine performance problem or electrical malfunction If the MIL is on, retrieve the DTC and follow the manufacturer’s recommended procedure to find the root cause of the problem OBD-II vehicles use a 16-pin DLC and common DTCs Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458