A fuse is a device designed to break a circuit, usually by melting when the current exceeds a certain value. Fuses are widely used in electronic equipment, but have been replaced by circuit breakers in household wiring. In the "old days" people would sometimes replace a blown fuse with a penny, which happened to be the same size as a fuse. Was this a safe practice? Why

High-voltage power supplies are sometimes designed to have a rather large internal resistance as a safety precaution. Why is such a power supply with a large internal resistance safer than one with the same voltage, but lower internal resistance?

Can all combinations of resistors be reduced to series and parallel combinations?

Old-time Christmas tree lights had the property that, when one bulb burned out, all the lights went out. How are these lights connected, in series or in parallel? How could you rewire them to prevent all the lights from going out when one of them burned out?

As I was driving down a bumpy road, my 1990 Cadillac Seville which had just gotten out of the shop (they removed the idle control motor to fix the constant acceleration problem) suddenly went dark.

Everything just shut off with an audible *click*. I mean the DIC, the entire electronic display (speedometer, gas, time, odometer, etc.) The click you hear when the Twilight sensor kicks on & off.

The headlights went off, the climate controls, everything. Engine kept running, brake lights & turn signals kept going fine as well.

Everything that was manually operated worked. I turned the headlights on manually, but otherwise, everything automatic about the interior electronics died.

They came on sporadically, especially when the engine was cold. However, that lessened to an occasional occurrence. Now, when the car dies, the interior electronics come to life, until I start the engine again.

I've checked all of the checkable fuses, not the odd box like (circuit breakers?) ones though. Any ideas out there? I desperately need a car for work, my family depends on it.

Each time I start the engine, the check engine light comes on as well.
About the power supply module, this may have happened, so to speak, when it was at the shop the first time, & was worsened by the bumpy road conditions. These guys replaced the turn signal/cruise arm on the column, which, because the Cadillac has the armored steering column, they would have to remove the dash.

Maybe they loosened or bumped & didn't tighten the power supply module.

Good thinking to the first reply, I will look up a schematic (If I can find one for free) & check it out.

Thanks! Will post back with my findings.