Automotive Diagnostic Service (914 views)
Automotive Diagnostic Service
Is your car not driving right? Or do you have a warning light on? Vehicle's today have a complex inter-related system. A warning light comes on when the computer senses a signal that one of the components or systems has gone out of its' normal operating range. Some of the causes of a warning light can be something as simple as not tightening your gas cap or a serious issue with your engine. This is why it's important to get your vehicle in as soon as possible to let professionals diagnose the issue.
Properly performing a complete diagnostic procedure normally includes the following steps:
1. RETRIEVE DATA - A full functioning scan tool is used to perform an onboard computer system analysis in order to retrieve the following:
- Computer codes
- Freeze frame data
- Computer software version numbers
- Critical sensor data and status information
NOTE: Merely “pulling codes” does not generally provide enough information to make an accurate diagnosis of the problem. Pulling codes is the initial step in the process by identifying the circuit or system that has illuminated the vehicle’s check engine light.
2. VERIFICATION TESTING - Verification tests determine if systems meet proper specifications. These tests may include an analysis of:
- Engine vacuum and backpressure
- Mechanical and electrical engine timing
- Ignition system
- Fuel system
- Emissions system
NOTE: Failure in any of these basic systems can cause the check engine light to illuminate and falsely identify a circuit or component as the problem, which could lead to improper or unnecessary parts replacement.
3. PINPOINT TESTING - All manufacturers require that circuit or component pinpoint testing is done in order to make an absolute diagnostic determination. These actions involve:
- Working through wiring diagrams
- Performing electrical and/or mechanical tests
- Performing bi-directional control tests
- Visual inspections of suspect areas
4. RESEARCH TECHNICAL SERVICE BULLETINS - Technical Service Bulletins and hotline information will indicate if the problem has been determined to be a pattern failure, meaning that it is a known issue that occurs with a particular type of vehicle. This does not eliminate the need for testing, as other systems must meet specifications before a service bulletin procedure should be performed.
5. CAR REPAIR - This may involve multiple actions such as:
- Parts replacement
- Cleaning of passages, connections and/or components
- Performing manufacturer technical service bulletin updates
- Updating of vehicle’s computer software
- Wiring repair or replacement