1. Diagnostic procedure Training for the future

2. So, where do we start? Diagnostic Procedure

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

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

5. So, where do we start? 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 Diagnostic Procedure Listen to the customer complaint Listen to the car’s complaint Loaded electrical light check

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

7. Diagnostic tools! Training for the future Diagnostic Procedure

8. Understanding DTC - P0123 P Powertrain B Body C Chassis U Communication 1 Manufacturer specific 0 Generic 1- 8 Specific area of concern Code ID Diagnostic tools Scan tool Training for the future Diagnostic Procedure

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

10. But, before one engages in diagnostic procedure, one must understand 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 Diagnostic Procedure

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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