Infrequent Complete Loss of Electrical Power Except Horn

[Frederick H.]

As I am in last minute rush preparations for the Regional in Frisco this week, my '63 340HP decides to quit while sitting at a red light at a busy intersection (near my house fortunately). The car is driven infrequently (more time in the shop of late than on the road) and has done this before. After shutting down, it recovers after about 15-20 minutes. All electric functions are dead except the horn. A dated post from when this first happened suggested if the horn still works and everything else is dead, it could be in the primary red wire that connects to the firewall/bulkhead. I checked the connection and it is okay. A new M&H wiring harness was installed a few (3-4?) years back.

Any updated thoughts on what would cause sudden loss of all electronics (except horn) and then resume after 15-20 minutes (heat dissipation?).

Thanks in Advance,
Fred

[Leif A.]

Fred,
Classic "red wire" syndrome. The harness can be new and the connection "look" good but still may not be making a good connection. The next time this happens, gently wiggle the inbound bulkhead connector and see if the car doesn't immediately restart. The "red wire" pin is in the lower corner of the inboard bulkhead connector. The pin may be misaligned and not making a consistent contact.
Also, even though the harness is "new" the car (as you say) has been sitting a lot lately...corrosion could be an issue. I would separate the connector and brush the connectors lightly with a soft wire brush and some Deoxit 5.