San Diego Auto Repair Experts

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Why a Diagnostic Charge?

When vehicles had fewer onboard computers and interconnected systems, a quick visual inspection could usually reveal a broken or worn part that needed replacement. Modern vehicles leverage the latest technology to manage everything from emissions to sound systems. Diagnostic equipment communicates with computers on your vehicle to obtain valuable data on what's gone wrong. Most data is vague or generic at best. The data points the mechanic in the right direction. Varying by the year of the vehicle, 1996 and newer cars, trucks, SUV's and Hybrids have on-board computers that can provide significant amounts of data, but not definitive answers. On 1995 and earlier vehicles, there is very limited data available through the computer, making it more labor intensive to figure out what is wrong.

A thorough diagnostic service involves many, often time consuming procedures. First, we connect the diagnostic scanner to your car, truck, SUV or hybrid and check for any malfunction codes. Real time data is also streaming from the vehicle's computer that we are able to utilize. For example, a trouble code stored in the vehicles computer indicates what area or system is malfunctioning. Armed with this information, our ASE Certified and Master Mechanics use their experience and troubleshooting skills to identify the cause of the malfunction and repair it. This process is aided by following diagnostic troubleshooting flow charts. The flow charts are basically a checklist with a series of different tests to be performed based on the mechanics belief of what caused the problem. Some diagnostic flow charts are very brief, while others go on for several pages. The mechanics knowledge and experience guide them on where to begin in the troubleshooting process.

Below are some examples of procedures that might be used in the diagnostic process.

  • 1. Talk to customer to obtain the most accurate information about their concern, review records of previous repairs and drive vehicle to confirm concern.
  • 2. Check databases for recalls, technical service bulletins etc.
  • 3. Visual inspection of suspect areas.
  • 4. Wiggle tests (of electrical connections).
  • 5. Connect scanner to obtain codes and/or inspect data stream.
  • 6. Perform electrical and/or mechanical tests of suspect component including lab scope patterns.
  • 7. Research for information on particular issue from places like Alldata, Mitchell, OEM Websites and the International Automotive Technicians Network (IATN) database.
  • 8. Check condition of the battery and alternator.
  • 9. Perform compression test.
  • 10. Perform leak down test.
  • 11. Perform vacuum test.
  • 12. Perform cooling system pressure test.
  • 13. Perform smoke test.
  • 14. Perform fuel pressure, quantity and quality tests.
  • 15. Check fuel injectors fuel spray pattern.
  • 16. Perform an emission test (4 or 5 gas analyzer).
  • 17. Examine ignition patterns on a scope or scanner.
  • 18. Check exhaust pressure.
  • 19. Check for grounds and power to components related with fault like relays, modules etc.
  • 20. Dynamometer test.
  • 21. Consult with other mechanics or tech support sites if problem is an unusually difficult one.

Diagnosing a vehicle is not always an easy process. To properly diagnose and repair a vehicle, an auto repair shop must be equipped with sophisticated, expensive equipment, subscriptions to technical information providers and most importantly employ intelligent and experienced ASE Certified and Master Mechanics to help keep labor costs affordable.

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