Weird electrical event 85 TD
 

Driving home from work on the expressway today I lost all electrical power. No electrical instruments, no windows, no turn signals but also no warning lights. Continued for about 8 miles. Then it all returned. Anyone have an inkling as to the source of the problem? Ignition switch? Battery terminals? I'm leaning towards the ignition switch. I'm thinking that if I lost a connection at the battery I would have gotten a battery no charge light on the dash? With the ignition switch off, none of those things would normally work, which I why I'm leaning in that direction.

If your ignition switch went off then the idiot light would come on as it would be trying to power the ignition circuits. If you turn the key off with no vac, the idiot light comes on. You could have had an earth strap problem or a fuse that had a bad connection. When things warm up & dry out strange electrical things happen.

I lean towards switch, too. If the battery lost it's ground, the spinning alternator would keep power until the diodes blew. I don't think the alternator can lose its ground. Never heard of that happening.

One way to isolate the key switch would be to check circuits that don't rely on the key switch. Did the clock stop over those 8 miles? On the expressway you'd have lost about 8 minutes. Did you check the dome lights?

Sixto
87 300D

Didn't think to check the dome light, that would have been an ideal test since it's not dependent on the ignition switch. It was too light to check the headlights. I didn't notice if the clock lost time and I'm not sure it was at exactly the correct time so I can't look at it now.

Sun spot flare up?

A few years ago my 240 would blink out power. It turned out that one of the terminals on the starter was loose. I took the wire off, tightened the terminal, put the wire back on, and the problem disappeared.
I had previously checked all the battery and chassis connections and those didn't fix it.

About two weeks ago I was driving the 240 to work and halfway there I was surprised to see the battery light come on. When I got there, I shut it down and tried to restart but got nothing at all. I popped the hood and to my surprised the positive side cable was completely off the terminal . . . just wasn't tight enough and slowly just worked its way off I guess.

So, may not be that extreme, but perhaps some poor connection someplace. Is your battery light working otherwise that it would come on if that was the case?

which car?

Sorry, 85 TD.

there is a socket above and to the right of the accelerator pedal, if it's loose, the exact situation will happen in an SD... also, the ignition switch will NOT start the car when this connector comes loose.

I'll check that.

what about fuses? I had something similar happen in my 85TD and after I rotated all the fuses it was back to normal.