1990 c2 intermittent loss of all functions
 

1990 c2 runs great, but intermittently will completely shutdown while driving, ie no headlights or hazards even, just completely dead. Thankfully it has come immediately back when driving. I can shut the car off after running normally and upon returning, everything is completely dead with no response from anything. Then after waiting a few minutes, everything operates as normal. Ive checked all the grounds and in dead condition I have power at the fuse block. In the dead condition, even the things that should work without the switch are dead with no response. Any ideas?

You can check the electrical part of the ignition switch as a starting point.

Battery cabling?

+1 on battery cables. My 964 acted just this way ocassionally until it finally stopped and wouldn't come alive again. Problem was in the negative battery cable. Both cables looked perfect and the battery terminals were clean and bright, but when I removed the negative cable it measured about 1,000 ohms instead of zero like the positive cable. Less than $20 bought a good quality replacement at a NAPA store and all has been fine ever since.

It makes sense to me that if it was the ignition switch, then the lights and the flashers would still work in the dead condition. I ohmed out the negative battery cable and it was zero, but im replacing it anyway and keeping my fingers crossed. It may be that resistance builds up in the cable while in operation to produce the failure?

Make sure to check and clean your ground connections.

Also check the resistance of the positive battery cable and make sure that the smaller wires that attach at the battery terminal are clean and tight.