Because the Oldmobile gods will not let me keep this thing running, I am having a new electrical issue. I was idling in the driveway after installing a new timing set, everything was running awsome. Just to push my luck I started fiddling with all of the lights and switches to make sure everything was ok. Well it wasent. After putting on the radio, heater/blower and wipers, I pulled out the headlight plunger and boom...car just turned off right then and there. I did not hear any pop, sparks, smoke, no anything. Now nothing works. It will not turn over, not even click. It is completly dead. I lost the daylight before I could start going over everything, just thought I would pick some brains before I get out there tomorrow. I was thinking the relay, but I just replaced that a few months ago. Any ideas? I want to drive this thing!!

 

Does the car still have its original wiring? and do you have a 1972 CSM or wiring diagram?

Quick check- check voltage at the battery (+) terminal, then check it at the junction block post. If it's the same, you've probably burned out the main harness fuse link at the JB as you had a substantial load on it. If no voltage at the JB post, the problem lies in the starter solenoid or battery cables.

There are three 10 gage red wires on the JB post. One is the power feed from the starter solenoid, one goes to the alternator, and the third one should have a short section of smaller gage black wire in it. That is the fuse link. The fourth red (18 gage) goes to the voltage regulator.

That fuse link feeds: the main lamp switch, the constant 12V bus at the fuse block, and the ignition switch, so without it nothing is going to work. EZ fix- any parts store will have a GM style fuse link. Do NOT use a regular wire in its place.

Hay- at least Olds made it easy to get to! You'd have to crawl under the car to fix one on a Chevelle!

 

Sounds like the Fusible Link from the junction block/horn relay as mentioned.

I used to blow mine all the time, until I realized exactly what it was, and NOT to use a 30a fuse! It is at least a 60a 'fusible link' wire IIRC.

 

I agree - check that out.
IF you replace the fusible link, be sure to solder it and use heat shrink tubing on the splice. Clean the old stub of wire with a dremel wirebruch before soldering it. Do NOT use crimp connectors, as they will fail too soon.

 

If I were you I would also check the rest of the harness. Something caused it to overload. It could just be that the wires are old and have built up resistance in them.

I ended up replacing the harnesses in my 70 and I can tell you it was some of the best money I have spent on any of my cars.