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Diagnostic procedure

Diagnostic procedure. Training for the future. Diagnostic Procedure. So, where do we start?. Training for the future. Diagnostic Procedure. Listen to the customer complaint. Listen to the car’s complaint. So, where do we start?. Loaded electrical light check. Carry out basic checks.

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Diagnostic procedure

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  1. Diagnostic procedure Training for the future

  2. Diagnostic Procedure So, where do we start? Training for the future

  3. Diagnostic Procedure Listen to the customer complaint Listen to the car’s complaint So, where do we start? Loaded electrical light check Carry out basic checks Check battery supplies Whilst car running Measure voltage Post to post 14.2 v DC voltage AC voltage must be less then 0.3 volts Training for the future

  4. Diagnostic Procedure Listen to the customer complaint Listen to the car’s complaint So, where do we start? Loaded electrical light check Carry out basic checks Check battery supplies Check battery grounds Disable car from start Block Measure voltage drop (whilst cranking) Negative Post to … All must be less then 0.3 volts Chassis Clamp Training for the future

  5. Diagnostic Procedure Listen to the customer complaint Listen to the car’s complaint So, where do we start? Loaded electrical light check Carry out basic checks Check battery supplies Check battery grounds Extract codes Codes OBD I & OBD II Inform customer Obtain budget commitment Training for the future

  6. Diagnostic Procedure Obtain technical information Supplies So, where do we start? electronic control module inputs outputs grounds Keep customer informed of progress Prepare invoice Diagnostics R and R Inform customer of final budget Training for the future

  7. Diagnostic Procedure Diagnostic tools! Training for the future

  8. Diagnostic Procedure Scan tool Understanding DTC - P0123 Diagnostic tools PPowertrain BBody Code ID CChassis U Communication 0Generic 1 Manufacturer specific 1- 8Specific area of concern Training for the future

  9. Diagnostic Procedure Oscilloscope Diagnostic tools So, you want to measure an injector pattern Back emf Supply Voltage Pintle bounce Ground Injection Pulse width Training for the future

  10. Diagnostic Procedure But, before one engages in diagnostic procedure, one mustunderstand how the system works and what the parameters ought to be (data list, waveforms,voltages, current, resistance etc). And above all 'should the component fail - what will the symptom be?’ Training for the future

  11. Diagnostic Procedure Throttle control How does the system work? Conventional throttle control TPS (input) Throttle body TPS input Ecm controls output timing injection etc electronic control module AF input Accelerator peddle Cable controls butterfly Training for the future

  12. M Diagnostic Procedure Throttle control How does the system work? Electronic throttle control TPS (feedback) electronic control module Electronic accelerator peddle Ecm controls motor (butterfly) Training for the future

  13. Diagnostic Procedure Sun-load sensor How does the system work? Single zone Dual zone Training for the future

  14. Diagnostic Procedure Catalytic converter How does the system work? + volts + volts time time Pre Cat Ox sensor Post Cat Ox sensor Catalytic converter Training for the future

  15. Diagnostic Procedure Sensors How does the system work? + volts Magnetic time - volts volts Optical time volts Hall Effect time Training for the future

  16. Diagnostic Procedure Current limiting How does the system work? No current limiting (ign coil) Linear current limiting (ign coil) Switched current limiting (injector) Training for the future

  17. + - + - Diagnostic Procedure Differential amplifiers electronic control module Inverting and non inverting Inputs How does the system work? + volts time electronic control module + volts time Training for the future

  18. Diagnostic Procedure TPS Should this component fail what will the symptom be? If there was a sudden drop in voltage? tps Training for the future

  19. Diagnostic Procedure Injector Should this component fail what will the symptom be? Good pattern at idle Good pattern snap throttle Good pattern back-off Training for the future

  20. Diagnostic Procedure Trigger module Should this component fail what will the symptom be? Good current limiting Uncontrolled oscillation bad current limiting Training for the future

  21. Diagnostic Procedure Ox Sensor Should this component fail what will the symptom be? Lazy Ox sensor Bad earth Snap throttle Closed loop Good Ox sensor Training for the future

  22. Diagnostic Procedure Immobiliser Should this component fail what will the symptom be? Electronic key Smart key reader Body control unit Electronic cont mod Training for the future

  23. Diagnostic Procedure Should one of these components fail How will it relate to customer’s complaint? Reading technical information Supplies (DC & AC) electronic control module inputs outputs grounds Training for the future

  24. Diagnostic Procedure Charging systems Reading technical information Engine running Ignition ON Ignition off System shut down Ignition off Engine starts Cranking Training for the future

  25. Diagnostic Procedure Hard wired What is CAN bus? Non - CAN bus systems ect ecm dashboard tcm (conventional system) air con other Training for the future

  26. Diagnostic Procedure Sharing of information Similar to a Fax machine What is CAN bus? Puts a message on the ‘BUS’ Other control units share information It is NOT unilateral ect ecm It is ‘Bidirectional’ dashboard CAN bus systems tcm air con other Training for the future

  27. Diagnostic Procedure How to diagnose What is CAN bus? DTC Myriad of DTC’s – which one would you tackle first? Must decipher which control unit is ‘logging’ the DTC code ecm CAN bus systems dashboard tcm air con Training for the future

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