ToyotaViejo

Very occasionally I turn the key to start, and nothing happens. Back the key off start to run, then go over to start and the truck cranks right up. 2-3 spins and it's running.

Today it did something weird, and even after looking through the wiring diagram, I'm no better off than I was.

I turned the key to start, heard a pop not unlike the armature in the starter moving and lost all power to the truck. No dash lights, no stereo, no nothing.

I backed it off to run and then over to start and it cranked right up.

So I hit the power lock button and the stereo briefly turned off and then right back on.

Drove it and parked. Was in the store for about 15 minutes. Turned the key to start and got the same bang I got this morning except this time, the stereo lost its presets so there was a full loss of power to all 12V systems. It lasted all of a split second.

Grounds look good, and I'm going out to get the battery/alternator tested on-board this afternoon.

Could this be a circuit opening relay problem? Ignition relay?