5 Steps to a More Accurate Diagnosis

Mitchell1 Color Blktag(5)In today’s vehicles, there seem to be fault codes available for virtually every monitored system. Because these systems interact with each other, it’s not uncommon to see multiple codes being set.

In many cases, diagnostic procedures will indicate whether additional fault codes may be set that share circuitry or depend on the actions of another system. As a rule, we expect the diagnostic procedure to lead us down the most efficient path to identifying and resolving the immediate problem, as well as the root cause of a fault code. Repairing a damaged circuit is likely only a temporary fix if we don’t determine what caused the damage in the first place.

Diagnostic procedures usually help us to dot our i’s and cross our t’s when we take the time to follow them. Having a diagnostic path to follow is a great help, even though it may appear a bit laborious at times. Some steps just sound pointless but should not be ignored.

For instance, why do we need to check the battery voltage when the voltage at the component is either clearly within specification or it is not! Well, perhaps some other system up the line to the circuit we are testing needs battery voltage to function. So, step-by-step diagnostic procedures can be a pain, but generally help to resolve concerns with the least amount of effort.

What happens when the problem we are confronted with does not have any published diagnostics — hope it gets assigned to another technician? Let’s say the concern ends up in our bay after all. What we can do is have a plan. And that plan can include these five steps to help lead to an accurate diagnosis.

  1. First, gain information about when and how the problem occurs. This is especially critical with intermittent issues. Having real-world information is essential. ProDemand with SureTrack from Mitchell 1 delivers information based on over 45 million actual repairs and returns the information specific to your vehicle. This includes Real Fixes for concise diagnostics for common failures along with causes and fixes related to multiple, simultaneous codes.
  2. Learn as much as possible about a system through the service information description and operation. ProDemand is an example of a resource for this type of auto repair information. SureTrack also offers an interactive community where you can ask questions and get answers from other professional techs who may have encountered the same issue you’re facing.
  3. Review the system wiring diagrams for circuits in the system as well as those circuits that tie in through shared power and ground connections. When possible, note harness routings to see potential movement or pinch points where damage may occur during operation. Also, be aware that splices tucked away inside a harness can be difficult to spot.
  4. Check for any heat sources near the circuit that may not be properly guarded or just routed too close. In addition, missing and damaged water shields could be allowing water to enter connections and result in short-circuits.
  5. Sometimes it may be necessary to systematically check a circuit. When that need arises, put together a checklist to indicate that a section of a circuit was inspected for an open, short to ground, short to power, or short to another circuit.

Granted, going to all this effort to identify a problem takes time and patience. Yet, these diagnostic skills pay off in the long run and make you as a technician all that much more valuable to your employer. And of course it’s always rewarding to track down and fix problems that go beyond the everyday fault codes.

For additional information, please visit Mitchell 1 or call 800-209-9043.

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