Chat with an old diesel tech flipped how I approach electrical gremlins

I was talking to a retired guy at the parts counter last Tuesday, and he told me to stop chasing voltage drops with just a meter. He said I should always load test the circuit first with a test light that draws a few amps. Sure enough, I had a crank-no-start on a 2002 F-250 where the meter showed 12.4 volts but the light barely glowed. Has anyone else had a bad connection that your multimeter totally missed?

2 comments

2 Comments

kellymurphy16d ago

Man that bit about the light barely glowing is exactly what happened to me on a 94 F-150. Multimeter said 12.6 volts all day, but a test light showed it was barely lit. Turned out to be a corroded fuse link that looked fine. I never trust a meter alone anymore after that.

brian30316d ago

You ever spent hours chasing a phantom drain only to find out your meter was lying to you? Yeah, I used to think a multimeter was all you needed until a bad ground on my buddy's truck showed perfect voltage but wouldn't start. That old timer knows what he's talking about, a loaded test light catches stuff a meter just ignores.