The first step I now take in vehicle diagnostics

The following four vehicles (which certainly are varied) all came to me for repair and I did not identify the root of their problems immediately. And that’s because I was staying stuck in my ways and not adapting to changing vehicles. Let’s examine.

• Situation One: A 2019 Nissan Versa sets a P0102 DTC.
• Situation Two: A 1978 Harley-Davidson FLH begins blowing black plumes of smoke, misfiring, and generally becoming unrideable at idle and under power.
• Situation Three: A 2014 GMC Terrain displays an inoperable backup camera.
• Situation Four: A 2013 Harley-Davidson Street Glide intermittently loses all gauge operation during high RPM, low throttle events.

That’s four very disparate vehicles, no? But all of the problems listed had the same root cause: the battery was not up to snuff.

So now, when I have a diag to approach, I check the battery first. Some of you probably do this as well. Those who do not? Maybe give it a whirl. The following video explains it pretty succinctly:

Solid advice here. Those momentary voltage dips can cause all sorts of havoc, and the worst part is that havoc often looks very different than the problems we expect to see from a bad battery, like the traditional dim lights or sluggish starting.

Succeed where I have failed. Test the battery. Save some time.