We use wiring diagrams in many of our diagnostics, but if we are not careful, they can sometimes lead us to make decisions that are not accurate, which can lead to wasted diagnostic time, unnecessary parts costs for the replacing parts that are not defective, and sometimes even missing a simple repair.
Whenever we get a vehicle in for one simple service and find a lot of other stuff that needs attention, any well-trained, reliable technician will make a list of the needed repairs for the customer, putting the safety-related ones at the top.
I encountered a stubborn apparition-infested 1998 Ford Explorer, 4x2, 5.0L. This vehicle, which had an automatic transmission, California emission, “believed” it was a four-wheel drive, but it had a two-wheel drive powertrain!
Every so often some of the vehicle problems we encounter can seem sort of paranormal. Even though we keep telling ourselves that there must be some logical explanation to what is causing the fault, the data we are observing is incomprehensible and our usual tried-and-true testing reveals little or no guidance.
I was recently called to a shop for a job that required strict adherence to a diagnostic strategy or else a lot of time could have been wasted on my part. I’ll review the steps I used to diagnose a 2005 Hyundai GX350.
The first step to diagnosing any parasitic draw starts with what’s being drawn down to begin with — the battery. I think more than any other component, the battery is the most overlooked item when it comes to testing for a parasitic drain.
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