My High Beams Blew Out My Power.

[slant67]

My '67 Slant 6 Barracuda hadn't run in a few years out of sheer neglect...There have been a few times in the last 20 years that she's been close to sorted out, but never completely. I am on a mission. It's time.
Today, I finally drive her. I had installed my new gas tank and rebuilt my carb, changed some fluids and she drove kinda great after fixing a few leaks of differing magnitudes
Pulling into the darkening garage tonight.... after nearly an hour of top-down cruise around town...I turned my lights on just to test them, clicked on my high-beams for good measure...and lost all power.
I look forward to putting in the time tomorrow night, running down whatever electrical malfunction, fuse, relay...short...whatever it might be...
But if anyone out there happens to know what's up, please let me know.
Thanks

 

[omahamoparguy]

something shorted (probably the high beam switch) and the fusible link burned (like its supposed to when there is a short. I's disco that high beam switch and test it with a meter.

 

[slant67]

thanks so much...that sounds easy enough (famous last words)

 

[67Dart273]

These girls are VERY under fused if you have the original wiring harness.

Please read these two articles

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

Now in the first article on the ammeter, there is this diagram:

This diagram is fairly accurate for many years of these cars. Your mail power comes off the stud on the starter relay, goes through the fuse link, and through the bulkhead connector (red wire,)

through the ammeter, and in the under--dash harness, a few inches away from the ammeter in the ammeter black wire, is the factory "welded splice."

Amoung other things, this branches off and feeds off to the ignition switch, the fuse box "hot" buss and the HEADLIGHT SWITCH.

In other words there is NO FUSE going to the headlight switch.

Now, the headlight switch has a BREAKER built into the switch. From there, power goes to the dimmer switch, and one or the other (hi / low) power goes out through the bulkhead to the lamps.

If you do not have one, download a factory shop manual here:

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

There's a lot of good info over at MyMopar, including somewhat usable diagrams. ALWAYS use the shop manual if you can. The MyMopar diagrams are sometimes useful for a "quick look". They are NOT complete when you get into options and connectors, etc

http://www.mymopar.com/index.php?pid=31

First thing to do is see if you have power at the "big red" wire going into and through the bulkhead, second thing is to see if you have power up at the ammeter

 

[crackedback]

First thing to do is see if you have power at the "big red" wire going into and through the bulkhead, second thing is to see if you have power up at the ammeter

Yep. Fusible link is likely cooked or the bulkhead connector. Also check condition of black wire where it passes through bulkhead.

Another good reason to install a headlight relay system on our older cars. Takes the load off all those 40 YO, insufficient wires.

You could continuity test the headlight plug high beam terminal back to battery ground with them removed from your headlights. Do it with the bulkhead disconnected as well to isolate the issue. That would be a no brainer on a compromised system if you had continuity.

 

[RedFish]

ok so we know something in the high beam circuit is shorted directly to ground.
the dimmer switch and its wiring is a likely place for this to happen.
Visual inspection should provide evidence like melted wire casing.
I have found the fault to be at the connection on the back of the bulb too.
good luck

 

[krazykuda]

Have you also checked the connector on the headlight switch. These sometimes get a loose connection and then run real hot and start to melt the connector that holds the wires in.

I've had many abodies with melted headlight connectors. Common issue...

 

[slant67]

Thanks again!

Faulty dimmer switch...replaced it...All was well.
Then, I realized it was my alternator that was behind many of my little electrical issues.
I look forward to begging you all for help again soon!