Admit your Garage Mistakes

[mike_nofx]

A couple of years ago I was installing a new stereo into a 1990 Nissan Patrol, I wired it up quite easily (have done many head unit installs) but when it come to wiring up the earth/ground wire of the had unit to the Patrols wiring, I connected it to the incorrect wire.

What I do is, turn on accessories, then ignition, locate all my wires ( acc 12, constant 12, ground etc) mark all wires, then wire in the new stereo harness.

Now I'm still a little confused to this day, maybe someone can enlighten me. The wire I selected in the Patrol to be my earth wire was grounded with ignition on, but became 12v+ with the ignition off. (I possibly have this slightly confused, it may have been ground with accessories, but 12v+ with ignition on or vice versa??) In what situation would a wire need to be Grounded, then switch to 12v+??

The result once I had finally finished wiring up everything was a working stereo... Until I turned off the ignition and met a puff of smoke from the stereo, due to the stereo ground becoming 12v!

Ground Wire insulation had melted off, and required a new wire to be soldered to circuit board, and a correct ground to be located, then all sweet!